Is My Sonya Salvageable?

She's salvageable. She won't be the absolute best in terms of Ploys since her resistance took a hit, but she's definitely not useless.

Yes, that is completely salvagable! It makes her similar to Tharja or a slower Nino. Slap on the speed or damage (spd pref) and she will be just fine.

EDIT: Find a new skill for C, she won't be able to ploy.