Remember Baha'u'llah translated means Glory of God. Recall also that one of the names of Jesus was Immanuel which means God with us.
There a number of different Messianic titles in the OT.
The Glory of the Lord
The Glory of the god of Israel
The Lord of Hosts
The King of Glory
The everlasting Father and Prince of Peace
The Desire of all nations
The Branch
Some verses refer to one Messiah or the other, some refer to both, and some also refer to God.
Comfort ye, comfort ye my people, saith your God. Speak ye comfortably to Jerusalem, and cry unto her, that her warfare is accomplished, that her iniquity is pardoned: for she hath received of the Lord's hand double for all her sins. The voice of him that crieth in the wilderness, Prepare ye the way of the Lord, make straight in the desert a highway for our God. Every valley shall be exalted, and every mountain and hill shall be made low; and the crooked shall be made straight, and the rough places plain: And the
glory of the Lord shall be revealed, and all flesh shall see it together.
Isaiah 40:1-5.
Afterward he brought me to the gate, even the gate that looketh toward the east:
And, behold, the
glory of the God of Israel came from the way of the east: and his voice was like a noise of many waters: and the earth shined with his glory.
Ezekiel 43:1-2
Lift up your heads, O ye gates; even lift them up, ye everlasting doors; and the King of glory shall come in.
Who is this King of glory? The Lord of hosts, he is the King of glory. Selah.
Psalms 24:9-10
For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The might God, The everlasting Father, The Prince of Peace. Of the increase of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. The zeal of the Lord of hosts will perform this. Isaiah 6-7.
And I will shake all nations, and the
desire of all nations shall come: and I will fill this house with glory, saith the
Lord of hosts.
Haggai 2:7
"And speak unto him, saying, Thus speaketh the
LORD of hosts, saying, Behold the man whose name is
The BRANCH; and he shall grow up out of his place, and he shall build the temple of the LORD: Even he shall build the temple of the LORD; and he shall bear the glory, and shall sit and rule upon his throne; and he shall be a priest upon his throne: and the counsel of peace shall be between them both."
Zechariah 6:12-13
We need to consider each verse on a case by case basis to work out which ones speak about the Baha'u'llah (Glory of God), which speak about Jesus, and which refer to both.