VIET has some flavor events for Byzantine/Greek characters; there's also a few things here and there in VIET Immersion, but that's not available currently.
SWMH expands on the Imperial Reconquest by making it a tiered system.
Meaning, the Emperor can always IR within the de jure ERE, but once he has that he can use it further, to take Sicily and the Balkans, for instance.
The target-able lands expand as you conquer the previous level, eventually allowing you to target the entire former Roman Empire.
Actually, it's PB & EMF with the tiered Imperial Reconquest CB, as SWMH doesn't touch any logic scripting-- SWMH is only history, map, CoA, cultures, and title localisation. But yes, you've got the rest right.
There's also [another] special law for the Byzantines: The Themata System has 3 slider levels of reform. Byzantium starts in the most decayed state of the 3 in all starts.
And, yes, I do have [currently somewhat muddy] plans for future expansion of ERE mechanics & flavor in EMF, and SWMH is [long-term] planning to overhaul the ERE history & map (more than they already have).
Are you certain that is the case? I'm running 2.1.6 right now with everything except EMF and PB and I've still got the tiered IR CBs.
I know, because I had to mod out the trait restrictions from that version.