...It is also possible that she was considered a 'useless' caster and her talents not put to good use. I doubt the last one as she was a 'master class' Croakamancer and I don't think she levelled all the way to there under Stanley/King Saline IV. She had to be practicing her arts in some way.
Remember though that she's a multi-talented caster. Even without scrolls she's able to cast from other disciplines (Sizemore was able to cast Shockamancy with scrolls and he's said he's not multi-talented, so Wanda being multi-talented must represent casting from other disciplines WITHOUT scrolls). So it probably wasn't her Croakamancy that she used a lot in order to level or to help FAQ.
I'm curious as to what she did actually do for them.