What is bizarre is making the claim that Acts is “about the Apostles.” Seven of them are mentioned only a single time in a single verse and nowhere else in the book. None are given any serious attention after the first few chapters.
Acts was written to show the Word of God being nurtured in Jerusalem, then moving out into Asia Minor, and finally traveling to Rome, in the process losing its Jewish audience and becoming very much a message to the Gentiles. That is the structure of the work.
It is not a simple historical narrative of the early Church. There is no mention of missionary work in Egypt, even though Alexandria was nearly as important as Antioch in the early church. There is no mention of Apostolic journeys to Syria (other than Paul and Barnabbas working in Antioch). Stephen’s martyrdom is mentioned because the flight of many Christians following that event led them to Antioch. We not only do not hear of the deaths of the Twelve (besides James), we do not hear of the works or words of the Twelve.
In structuring the work, the growth of the Word is shown to occur in Jerusalem, then Israel and Samaria, then Antioch (with the opening of the Word to the Gentiles), then Greece, then, finally, to Rome with the ever increasing reluctance of the Jews to listen to the Word. All other events are subservient to this schema. In fact, once Paul takes center stage, nearly all the other players simply fall away and the narrative focuses on Paul, alone.
If Acts was intended as a simple church history, then the fierce confrontation between Paul and the leaders of Jerusalem regarding the acceptance of Gentiles and Jewish Law should appear the way that Paul describes it in Galatians 2. Since the intent is to simply show that the Word has spread to the Gentiles, those disputes are couched in different words to minimize the original opposition to the acceptance of Gentiles. In other words, the book has a different purpose than a simple journal.
We cannot use the book to establish dates beyond its writing, because it was not written to identify dates or to provide a timeline. Dates within its narrative appear to be accurate, but events outside its narrative are simply outside its narrative, not necessarily unknown to the author.