The Catechism of the Catholic Church says (#105), "God is the author of Sacred Scripture." Further, (#106)
[The human authors of scripture]consigned to writing whatever he wanted written and no more."
Therefore, there is no part of the scriptures that is merely human and potentially erroneous. God is Truth, and can neither deceive nor be deceived. Thus, I believe that the answer to your question is that all of Genesis is to be considered historical, unless there is a reason to believe that the literal sense is different (as has been suggested with Genesis 1).
In the area historical accuracy, the Old Testament has been proven a very reliable witness to the ancient, ancient world. One should be careful about finding historical inaccuracies there, because the authors of the Old Testament, even at the latest date argued for the time of writing, were far closer to the events and society of the times they depict than we are.
A little anachronism is to be expected in human language. For instance, we often talk about things happening in Israel or Turkey when it is only a geographical accident that they are included in the current borders of the political entities that bear those names today. That doesn't make the statements any less true.