I have played rtw, mtw2, etw, ntw(their mods). There are some suggestions I think would greatly helpful and effective for historical gameplay of EB2:-

(1)- When I was playing EB1.1 I saw that Romani faction(going under AI), which historically conquerd gallic provinces including much around medeterrarian sea, was destroyed by both gallic factions. this is a great historical inaccuracy. there should be some faction power parameters or programming which make factions(under AI)to go according to history.

(2)- Hoplites should be able to form some testudo like(made by roman legions) formation, as we saw in movie troy made by acklies(Braud Pit).

(3)- There should be weather fatigue(in winters) and area fatigue(for examples, for romans in far german nd british territories nd far eastern deserts. similarly for greeks in far scythian areas and indian territories). This fatigue factor is extremely necessary to make gameplay historically accurate.
Thanks