Hey there ! Cool mod you made here. It actually makes my WRE and WRE-based factions campaigns feel more grounded in the reality of the 5th century AD - having roman armies rely a lot on foederati, especially Salian Franks and Taifali.
Some more units from the Alani and even the Huns could make for fine additions, as the Romans did recruit them even in the West for some campaign. Maybe some sarmatian heavy cav cataphracts, and horse archers as well ? Some elite hun cav could be added as Bucellarii. To add more berber ones, Amazigh raiders and numidian cav would make fine additions as well. Definitely need more cav in WRE. With the settlement of Visigoths and Burgundians in Gaul, it wouldn't be bad either to add Gothic warriors and Gothic Palatina, goth archers and slingers, as well as burgundian elite scattershot slingers and barbed javelinmen.

I know this seems a lot, but they are mere suggestions you can pick from if you feel like it.

Hope you do well.

Only Foederati spears and Taifali are different

how are they different from in game version except you can train them? Lookd same to me.

Hurrah, Equites Mauri!