They were not greeks and they had a different culture, however their dependence and interference in the greek world puts them really close to the “Hellenic group”. Their culture crumbled every time they differentiated themselves from the Greeks and there were Greek cities in their lands. They spoke the greek language even though it wasn’t theirs. There were disputed lands between them Macedonia and Epirus, both of which are definitely part of the Hellenic culture group. Lastly we don’t really know how much their culture had evolved at the time or how dominant their culture was (less is known about them than tribes in Africa). These are the facts and yeah they don’t convince me much either, that they should be part of the Hellenic culture.

However we are talking about a game. In order for the game to play out closer to history I guess they had to make sacrifices in historical accuracy like they did with Turkish culture in eu4 (it is present in lands it shouldn’t for stability reasons). Gamewise if they are part of the Hellenic group they will try to interact with Greeks more I guess, or they might try to expand that way.

In which culture group would you put them? Would you create a new one for just 2 provinces?