It seems to be the case that the ancient Macedonians were for a long time only half-accepted as a Hellenic people, and their full inclusion inte the "family" occurred only after Alexander's death, when the Macedonians and the Greeks had to coopterate to remain the dominated class in the Diadochi states. Historians even dispute whether the ancient Macedonians (before their Atticisation) spoke a Greek dialect or a Thraco-Illyrian language.

It is also known that the Getai as well as other Thracians were prone to adopt some Hellenic influences.

I don't know if this would be historically possible (i.e is it possible that history could unfold this way?), but if so, then I would suggest that the Getai, if the player conquers Hellenic land (like Makedonia, Epeiros or Hellas) have some reforms available which make it possible for them to be even more Hellenized, like getting some more Hellenic-inspired units and building temples instead of groves, yet of course keeping some distinct Getic influences (like for example worship of Zalmoxis and falxmen). Hellenization of another people, after the Macedonians.

Just like the Pahlava and the Hayasdanis have reforms that Persianize them due to their historical relations with the Persian people, the Getai could have reforms that Hellenize them. The Greeks didn't really hesitate to Hellenize others whenever possible.

Maybe EB 1.0 is the absolute final version that will be made for RTW, but if it is not, then please consider this suggestion. If this would not be historically possible, i.e such reform possibilities would not be historically accurate, then please tell me that.