I had a similar thought about some of that.
“And the holy city shall they tread under foot forty and two months”; that is, the Gentiles will seize and subdue Jerusalem for forty-two months, or 1,260 days, or — each day being equivalent to a year — 1,260 years, which is the duration of the Qur’ánic Dispensation. For according to the text of the Bible each day is a year, as it is said in Ezekiel 4:6: “thou shalt bear the iniquity of the house of Judah forty days: I have appointed thee each day for a year”.
‘Abdu’l-Bahá, "Some Answered Questions", 11.5
That does look problematic definitely. I do have a logical mind. But you can be too literalistic. He specifies 1260 years as the duration of the Qur'anic dispensation. Does that automatically mean that Jerusalem was conquered at the time of the start of the Qur'anic Dispensation? The others could be looked at similarly, though 'Abdu'l-Baha doesn't mention that 1260 is the duration of that Dispensation.
Sorry, that's the best I can do. Prophecies are not the real bass of proof for the Baha'i Faith. The real proofs lie elsewhere. Prophecies are there to perhaps confirm the faith of someone who is already a believer. They are also there to test humankind, especially those who look at prophecies first. Read the Book of Certitude. It has something to say on that theme. It is interesting, though, that there are 1260 lunar years between 621 and 1844. That does say something if you don't have a disbelieving mind. It is the same with Daniel I have concluded. It has 2300 years from a certain date, 1260 like in Revelations, 1290 that seems to fit well concerning Baha'u'llah. There are details in that can be troubling, I admit. But try to look at the big picture of all of the evidence for the Baha'i Faith in totality. I have failed myself at times to do that in my life as a Baha'i. I have had a skeptical mind.