Besides being over-heated she might instead have been over-exposed to mite killing chemicals...they can cause neurological damage too. Poor little snake...
Many BPs that are sold to pet stores don't do well, as often staff is not experienced enough or have the space to do things the right way, much less the time or patience
to get them to eat properly.
Her body weight looks pretty good now, but I can see why your vet gave it the label that he did. You have a "special needs" snake, whatever caused this you may never know for sure...but it's best she stays in a low-stress environment...other than that, not much you can do.
And for what it's worth, I'd have tube-fed her too.to your vet...