Before 1.36 went off the deep end with in some cases wholly artificial debuffs, a user on Steam named RMS_Oceanic made a whole series of wonderful flavor mods for ERE. Likewise, there is an older mod last updated for 1.34 (I believe) called Renovatio Imperii, which is also packed with more flavorful starting events to make the start less RNG, as well as a CK2-inspired CB to conquer former Roman lands (that funny enough PDX gave to Italy in recent official DLC).

RMS_Oceanic's mods are as follows:
Byzanium - Council of Florence and the Union Revolt: a less annoying & more sensible disaster at start
Byzantium - Gemistos Plethon: flavor events about the man, set up as springboard into reviving Hellenism
Byzantium - Aegean Events: Cores on all Greek provinces after recovering mainland Greece
Byzantium - Monuments: Includes several that EE & FU don't have (to my knowledge)
Byzantium - Expanded Triumphs: just more flavor in general
Byzantium - Enhanced Byzantine Culture: a lot of intriguing flavor for culture after reconquest
Byzantium - Declare the Roman Empire: makes the decision easier to achieve, but also just a name change.
Byzanium - Varangian Guard and other Mercenaries: adds a bunch of interesting merc groups.

Renovatio Imperii adds a bunch of flavor events, particularly at the start to make it less RNG w/o being gamey, as well as a CK2-inspired CB to reconquer Roman lands, which funny enough PDX gave the same CB to Italy in recent official DLC.

Idk if a full reworked tree is planned for BYZ in the future to replace the FU one, Stiopa, but if so, I hope you take inspiration from these mods to do so, if simply merging their contents into the current FU one is impractical.

Thank You for all your work on EE so far, hope you have a nice weekend!