Very interesting background. Herodotus (of course a bit earlier) spent a fair bit of time in the first few books talking about Egypt, it's geography e.g. various mouths of the Nile, and how Greek Mercenaries fought there. It seems amazing how much they mixed, lacking modern transport.
I am not nearly as expert as you (though I have heard of Origen and Antony, mostly wrt the early Church), but IIRC Alexandria was a bit like the Bosphorus a cultural melting pot due to trade, were a few heretical (I think Arians) Bishops arose. I don't recall what period the Rosetta stone was dated to, but it sounds like the right region.
Evagrius Ponticus, a Byzantine monk who joined the predominantly Coptic speaking monastic communities at Nitria and Kellia in the late 4th century, records in his texts the ethnic tension between the rural Coptic speaking intellectuals and the metropolitan Greek speaking intellectuals.
I have never come across this, it sounds fascinating, a bit of old Egyptian vs Greek culture clashing? This sounds maybe a little bit like a divide between rural Latins and cosmopolitan urban Romans (or nothing like it at all probably, mostly from 'Marius the Epicurean'), were some older traditions survived longer in the country.
How pharaonic religious ideas and cultural trends continued after the Greek colonization is a huge problem for historians that requires a lot of reading of sources and examination of archeological remains.
Yes! Unless historically studied, it tends to get glossed over in favor of politics, battles and the ebb and flow of dynasties (Egyptian, Greek, Roman, Byzantine) up to the Arab conquest.
How pharaonic religious ideas and cultural trends continued after the Greek colonization is a huge problem for historians that requires a lot of reading of sources and examination of archaeological remains.
That lovely and vexing mix of Archaeology and History. Are some of the earliest, most important documentary sources (outside of the vatican and museums), held in places like St Catherines Monastery?