Nice work +rep!
The starting date is 1243, isn't it? Why don't you call the Byzantine Empire as the Empire of Nicaea? Is it possible to make a script that allows the first Byzantine successor state that captures Constantinople to change the name and possibly units & flag to the original Byzantine ones (of course it would be called Eastern Roman Empire)? Something like Eriador --> Arnor in TATW?
By the way, when will this mod be released (roughly speaking)?