And if you want me to administer the coup de grace to your argument here are Baha'u'llah's further words to Queen Victoria - not to other kings according to your interpretation...
"O ye rulers of the earth! Wherefore have ye clouded the radiance of the Sun, and caused it to cease from shining? Hearken unto the counsel given you by the Pen of the Most High, that haply both ye and the poor may attain unto tranquillity and peace. We beseech God to assist the kings of the earth to establish peace on earth. He, verily, doth what He willeth.
O kings of the earth! We see you increasing every year your expenditures, and laying the burden thereof on your subjects. This, verily, is wholly and grossly unjust. Fear the sighs and tears of this Wronged One, and lay not excessive burdens on your peoples. Do not rob them to rear palaces for yourselves; nay rather choose for them that which ye choose for yourselves. Thus We unfold to your eyes that which profiteth you, if ye but perceive. Your people are your treasures. Beware lest your rule violate the commandments of God, and ye deliver your wards to the hands of the robber. By them ye rule, by their means ye subsist, by their aid ye conquer. Yet, how disdainfully ye look upon them! How strange, how very strange!
Now that ye have refused the Most Great Peace, hold ye fast unto this, the Lesser Peace, that haply ye may in some degree better your own condition and that of your dependents.
O rulers of the earth! Be reconciled among yourselves, that ye may need no more armaments save in a measure to safeguard your territories and dominions. Beware lest ye disregard the counsel of the All-Knowing, the Faithful.
Be united, O kings of the earth, for thereby will the tempest of discord be stilled amongst you, and your peoples find rest, if ye be of them that comprehend. Should any one among you take up arms against another, rise ye all against him, for this is naught but manifest justice. Thus did We exhort you in the Tablet sent down aforetime, and We admonish you once again to follow that which hath been revealed by Him Who is the Almighty, the All-Wise. Should anyone seek refuge with you, extend unto him your protection and betray him not. Thus doth the Pen of the Most High counsel you, as bidden by Him Who is the All-Knowing, the All-Informed.
Beware lest ye act as did the King of Islám when We came unto him at his bidding. His ministers pronounced judgement against Us with such injustice that all creation lamented and the hearts of those who are nigh unto God were consumed. The winds of self and passion move them as they will, and We found them all bereft of constancy. They are, indeed, of those that are far astray."
And we all know what happened to the "King of Islam" aka the Sultan Abdul Aziz don't we!
So your argument that Queen Victoria's letter was positive and prophesied the continuation of her kingdom fails miserably. If you take it the same way you are taking the Czar's letter, there is both commendation and condemnation in both. And Queen Victoria stood to suffer a fate every bit as ignominious as the Sultan of Turkey and the Czar of Russia if she disregarded the counsel of Baha'u'llah. She did disregard it - she did not suffer the immediate penalty. Neither did the King of Berlin, Emperor Franz Josef or the Pope.
Quite frankly, I think this whole prophecy thing is clutching at straws to shore up an outmoded faith that can no longer be sustained in the light of scientific discoveries and the unfolding of 20th and 21st century human history.
I do believe that Baha'u'llah wrote some incredibly sensible counsel to those Kings - especially about democracy and the profligacy of warfare - but these were neither new ideas (revelations) nor prophecies. If you take out the supernatural rubbish and admit that the religion is syncretic you have a reasonable set of principles on which to build a 21st century religion. But you would have to admit that Baha'u'llah was, at best, a wise man and that his thoughts are part of the progressive 'revelation' of human, not divine, wisdom. But you tarnish both the religion and the humanness of its origins in your desperation to bolster your founder's reputation with spurious claims of prophecy fulfilled. He didn't even write them as prophecy as far as I can tell, just counsel and warnings that were almost universally ignored.