Actually,it would work. I've experimented giving Romani FMs general's stars and stuff so that they would pose more of a challenge against my Arverni.

The difficult part comes when you cross cultures. How the heck do you give traits to an Arverni captain who had been bribed, only to get a Roman Man of the Hour, then was bribed back again, and whose name is 'Morbhe Cornelius Blasio'? I have no idea how that works now since he doesn't have an original FM name.