Regarding the new province layout, I could inagine Akhmim and Girga having theur religion changed to Coptic.
After all, there are 6 more provinces in Upper Egypt
And still not a single one with a Christian majority, sorry.
Akhmin and Girga are even regional capitals for the Muslim Amirs of upper Egypt for much of the timeframe.
The existing Coptic events for conquering Egypt will remain the extent of the Egyptian Copts in 1.23.