Anthony 说:
Yes, it'd be nice to have some well done Romans to play with. Though, once you get to Gauls, just some suggestions; no axes (La Tene Celts didn't use them, except Raetians and Goidils, and niether of them were really 'Celts' in the strictest sense), and lots of javelins and spears, and of course swords of various length and type. When you do get to that, I do have a grasp of what we know of ancient Celtic terminology, and could help with appropriate names for Celtic weaponry and armor.
Not attempting to rush you by any means, just offering some help. I think you should take your time. Better it all be done right than done fast.
Gauls from France were conquered by the time of the inclusion of Lorica Segmenta, if your going for historical accuracy. The enemies of barbarians I could figure for Rome would be British Celts, Dacian's from Eastern Europe, and germanic barbarians.
That's if your going for historical accuracy of course.

I dont know if it's out of your scope of the mod, but it would be interesting if you had some presence of the Parthians. Perhaps Parthian Horse archers + Cataphracts as the type of Black Knights from Vanilla M&B.