You are right, that is another reason that Christians reject Baha'u'llah, they don't believe anyone else but Jesus will ever be needed, but that presents a serious problem, because would leave all the Messianic Age prophecies unfulfilled, since Jesus was never planning to return to earth.
The Bible verses of the first coming of the Messiah don't mention the year Jesus was born either.
Daniel accurately predicted the first coming of Christ, and I believe he also accurately predicted the second Coming of Christ, who was the Messiah the Jews have long awaited. Here are some excerpts from a chapter entitled:
10: TRADITIONAL PROOFS EXEMPLIFIED FROM THE BOOK OF DANIEL
The proofs are explained in this chapter, following the two paragraphs below.
“All the peoples of the world are awaiting two Manifestations, Who must be contemporaneous; all wait for the fulfillment of this promise. In the Bible the Jews have the promise of the Lord of Hosts and the Messiah; in the Gospel the return of Christ and Elijah is promised.
In the religion of Muḥammad there is the promise of the Mihdí and the Messiah, and it is the same with the Zoroastrian and the other religions, but if we relate these matters in detail, it would take too long. The essential fact is that all are promised two Manifestations, Who will come, one following on the other. It has been prophesied that in the time of these two Manifestations the earth will be transformed, the world of existence will be renewed, and beings will be clothed in new garments. Justice and truth will encompass the world; enmity and hatred will disappear; all causes of division among peoples, races and nations will vanish; and the cause of union, harmony and concord will appear. The negligent will awake, the blind will see, the deaf will hear, the dumb will speak, the sick will be cured, the dead will arise. War will give place to peace, enmity will be conquered by love, the causes of dispute and wrangling will be entirely removed, and true felicity will be attained. The world will become the mirror of the Heavenly Kingdom; humanity will be the Throne of Divinity. All nations will become one; all religions will be unified; all individual men will become of one family and of one kindred. All the regions of the earth will become one; the superstitions caused by races, countries, individuals, languages and politics will disappear; and all men will attain to life eternal, under the shadow of the Lord of Hosts.
Now we must prove from the Holy Books that these two Manifestations have come, and we must divine the meaning of the words of the Prophets, for we wish for proofs drawn from the Holy Books.”
Some Answered Questions, pp. 39-40
If you do the math, the Bible predicted the first coming of Jesus to the exact year and it predicts the second coming to the exact year.
Daniel 12:8 And I heard, but I understood not: then said I, O my Lord, what shall be the end of these things?
Daniel 12:9 And he said, Go thy way, Daniel: for the words are closed up and sealed till the time of the end.
Daniel 12:12 Blessed is he that waiteth, and cometh to the thousand three hundred and five and thirty days.
The 2,300 years came in
1844 and the book was unsealed by Baha’u’llah. That math is explained in Some Answered Questions,
10: TRADITIONAL PROOFS EXEMPLIFIED FROM THE BOOK OF DANIEL.