I think, It is good that you look into those details.
Now, to analyze those quotes that you provided, and make a fair conclusion, first I think we need to know a little more about the cultural and religious background of 19th Century Persia, as well as the idea of Manifestations or Messengers of God, as Bahai Scriptures teaches.
In Persia, most Muslims believe that the Messengers are given Knowledge, only once their mission begins. In another words, generally, they do not believe that Muhammad knew He was a Messenger of God, or had knowledge of Quran, prior to beginning His mission.
In Bahai Scriptures though, it teach that, the Manifestations are aware of this, and know all things, from when they are born, however, They do not declare Their Mission or station, until the appointed 'Hour'. For Bahaullah, the Declaration of His mission was not until year 1863.
Thus, anytime prior to this date, Bahaullah did not reveal His station to people, and that He acted as an ordinary Person.
It is obvious then, when Bahaullah was a child, His parents did not know He is a Manifestation, and that He does not require education, thus, just as it was custom, they provided some elementary education, which included basic reading, poetry, basic reading of Quran, Calligraphy, as well as swordsmanship and horsemanship, as these things were what the Noble class taught to their Children.
The Book of Certitude was also written by Bahaullah, about a year or two, prior to declaration of His station and mission, thus, He is not speaking in it explicitly as a Manifestation of God, but rather as an ordinary person.
Even after Bahaullah declared His mission, He still presented Himself, compatible with the level of understanding of people of His time. For example, Bahaullah wrote to the King in this manner:
“I was but a man like others, asleep upon My couch, when lo, the breezes of the All-Glorious were wafted over Me, and taught Me the knowledge of all that hath been. “
Bahá'í Reference Library - Bahá’u’lláh, Pages 25-26
It is obvious that, this statement of Bahaullah appear to be contradictory, to the belief that Manifestations are not a man like others, but They know all things from childhood. But still Bahaullah speaks to the king according to the level of the understanding of the people of the time. It is like when a wise adult speaks with a child, He would speak in a way that the mind of the child could still accept, and not according to absolute Truth. As the King was a Muslim and believed Messengers have no prior knowledge of their Revelation, Bahaullah also presented Himself in that Manner. However for Bahais, Abdulbaha explained that verse:
"We come to the explanation of the words of Bahá’u’lláh when He says: “O King! I was but a man like others, asleep upon My couch, when lo, the breezes of the All-Glorious were wafted over Me, and taught Me the knowledge of all that hath been. This thing is not from Me, but from One Who is Almighty and All-Knowing.”[72] This is the station of divine revelation. It is not a sensible, but an intelligible reality. It is sanctified from and transcendent above past, present, and future. It is a comparison and an analogy—a metaphor and not a literal truth. It is not the condition that is commonly understood by the human mind when it is said that someone was asleep and then awoke, but signifies a passage from one state to another. For example, sleeping is the state of repose, and wakefulness is the state of motion. Sleeping is the state of silence, and wakefulness is the state of utterance. Sleeping is the state of concealment, and wakefulness is that of manifestation.
For example, in Persian and Arabic it is said that the earth was asleep, spring came, and it awoke;
or that the earth was dead, spring came, and it found life again. These expressions are comparisons, analogies, similes, and figurative interpretations in the realm of inner meaning.
Briefly, the Manifestations of God have ever been and will ever be luminous Realities, and no change or alteration ever takes place in Their essence. At most, before Their revelation They are still and silent, like one who is asleep, and after Their revelation They are eloquent and effulgent, like one who is awake."
Baha'u'llah also referred to (I mean read) books in order to answer questions as he (Baha'u'llah) himself admits in the Book of Certitude (page 184)
"For instance, a certain man, reputed for his learning and attainments, and accounting himself as one of the pre-eminent leaders of his people, hath in his book denounced and vilified all the exponents of true learning. This is made abundantly clear by his explicit statements as well as by his allusions throughout his book. As We had frequently heard about him, We purposed to read some of his works. Although We never felt disposed to peruse other peoples’ writings, yet as some had questioned Us concerning him, We felt it necessary to refer to his books, in order that We might answer Our questioners with knowledge and understanding. His works, in the Arabic tongue, were, however, not available, until one day a certain man informed Us that one of his compositions, entitled Irshadu’l-‘Avám, could be found in this city. From this title We perceived the odour of conceit and vainglory, inasmuch as he hath imagined himself a learned man and regarded the rest of the people ignorant."
Does it not seem odd that having granted Baha'u'llah divine insight into the entire wealth of Abrahamic, Zoroastrian, Buddhist and Hindu scripture and tradition, He was suddenly either unable or unwilling to directly reveal the contents of a direct attack on the "exponents of true learning" and this divine Manifestation had to resort to looking it up in a document written in a language he had never studied???!!! (NB - the last sentence in that quote directly from Baha'u'llah is priceless in my opinion - I can't help thinking of kettles, pots and the colour black for some reason).
Now with the aforementioned let's look at the Quote from Iqan. Bahaullah speaking as an ordinary person who still does not want to reveal His station, is narrating that, someone came to Him and asked Him about somethings that were written in a book, and that book was not still available in the city. It is obvious that, Bahaullah cannot give answer to the Questioner about what is written in the book, before the book is available. Perhaps the Questioner would ask Bahaullah, how would He knew what was in the book when the book is still not available? Thus Bahaullah, had to appear as an ordinary person, who reads a book after it is available. What is noteworthy, is, Bahaullah does not actually say, He read the book for 2 days. He says that, He 'kept' it for two days. It seems Bahaullah outwardly is acting as an ordinary person who reads the book to give a knowledgeable answer to the Questioner.
For example Baha'u'llah's own (older) sister (who would have known him as well as anyone) wrote (in a letter to Abdu'l Baha titled Tanbih al-Na’imin):
"He [Baha'u'llah] wouldn’t disengage from learning the rudiments for a moment. After studying the rudiments of Arabic and literature he inclined towards the science of philosophy (hikmat) and mysticism (irfan) so that he might benefit from these. It was such that he would spend most of the day and night socializing with high statured philosophers and the gatherings of mystics and Sufis... he (meaning Bahaullah) was a man who had seen most of the words and phrases of the mystics and philosophers and had heard and understood most of the signs of the appearance (of the Mahdi) . . . after returning from Badasht and after the Shaykh Tabarsi Fort war was over, he was engaged day and night in socializing with great Islamic scholars and followers of mysticism..."
As regards to the letter written by the half sister of Bahaullah, we know that this half sister had become Azali, which was another group lead by Yahya Azal, who showed animosity toward Bahaullah. In this letter she is trying to refute Bahaullah. But even if we assume, what she says in the letter is true, there is nothing in the letter, suggesting Bahaullah was learning a great deal. She is only referring to elementary education that Bahaullah would have recieved as a child. What is extraordinary about Bahaullah, is, as a child He was the one who explained things to scholars, rather than He learns from them. For example this is an example:
"Baha'u'llah had already, prior to the declaration of the Bab, visited the district of Nur, at a time when the celebrated mujtahid Mirza Muhammad Taqiy-i-Nuri was at the height of his authority and influence. Such was the eminence of his position, that they who sat at his feet regarded themselves each as the authorised exponent of the Faith and Law of Islam. The mujtahid was addressing a company of over two hundred of such disciples, and was expatiating upon a dark passage of the reported utterances of the imams, when Baha'u'llah, followed by a number of His companions, passed by that place, and paused for a while to listen to his discourse. The mujtahid asked his disciples to elucidate an abstruse theory relating to the metaphysical aspects of the Islamic teachings. As they all confessed their inability to explain it, Baha'u'llah was moved to give, in brief but convincing language, a lucid exposition of that theory. The mujtahid was greatly annoyed at the incompetence of his disciples. "For years I have been instructing you," he angrily exclaimed, "and have patiently striven to instil into your minds the profoundest truths and the noblest principles of the Faith. And yet you allow, after all these years of persistent study, this youth, a wearer of the kulah,(1) who has had no share in scholarly training, and who is entirely unfamiliar with your academic learning, to demonstrate his superiority over you! "
The DAWN-BREAKERS---Chapter V
And finally, here's a quote from a Baha'i library source from an article written about Baha'u'llah's 2-year reclusion in Kurdistan during which he renewed his propensity for religious dialogue with the Sufis.
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I think I'll probably leave this particular aspect there for now - unless you can give some references or evidence that actually shows that Baha'u'llah lacked religious and linguistic knowledge gained from learning.
As I am also originally from Persia, when I was going to school, I and other Iranians also took many courses in Persian Poetry, Arabic, Quran and Islamic studies up till grade 12. No body would have become a religious scholar or expert in Quran or fluent in Arabic, or be able to remember all Traditions and verses word for word after all, as those give only very basic knowledge. That is why in Persia, there are special schools for Religious studies.
