I always just assumed Kefka was a general, considering he had so much influence with Gestahl and power within the Empire. He didn't seem like he was just some ordinary solder. At the very least a ranked officer.

Although I did forget about that base scene dialouge. It's been a few years since my last playthrough on VI.

Although I could chalk some of it up to translating errors as been pointed out. Considering how little time Woolsey had for the translation of VI (1 week I think, or maybe I'm thinking of SoM.)

But yeah there isn't a whole lot about Kefka's past either way. All we really git is that tidbit on his under going the magitek knight experiments and losing his mind afterwards.

Either way though Kefka still is one of the better videogame villians I say.