Are the quick prep feats (faster battle prep specifically) working as intended? If so, then can you look at the random roll variance for backfiring when casting a spell?
I ask because there's a large variation in results that I get when casting immediately when I see "You feel fully prepared..." and when I wait for a while after that message appears.
I go from "badly backfiring" to being able to cast it successfully. So it seems that the messaging is showing earlier for the faster battle prep, but I'm not actually preparing it faster?