The massive Arabic Christian history begun by Severus ibn Mukaffa in the 9th century and running down to our own times is a gem. But I was looking at Google books today, and found a statement here in vol. 1 p. 211 of the Cambridge History of Egypt that the English translation published in Cairo in the 1950’s is unreliable. The first four chunks were published by B. Evetts in the Patrologia Orientalis, are presumably sound, and are here. 5 chunks of the Cairo publication are at this site, and 3 more exist. It’s a very hard book to get hold of, as I can testify!
This is the sort of thing that makes me wish that I was a rich man. I’d just hire someone and fix the translation.