Pony Fantasy VI Remake

Just because you didn't touch Terra directly/specifically doesn't mean something like this can't happen.
I'm not sure but if I had to guess, I'd say somehow her battle graphics pointer is not correct. But, just getting back I've yet to read all what you've done this past week, so I'm not sure where to start. Any patches at all used? And when is your last backup that works? Hopefully you should have made one pretty much after doing every little thing since you've learned how these random shits can happen...? I mean you should be able to narrow down what might have caused it from your backup, then tracing your steps.

I say her graphics pointer because this looks very similar to a mistake that happened to a character when expanding battle graphics & palettes for an additional character to be shown correctly in battle, but I doubt you were dabbling in that. But if some patch was used...I dunno.
And sure, you can fix it and not have to start from the backup, but you'll need to know what caused it.