I think Wizard is busted because of the spell scroll bug.

First of all, you shouldn't be able to scribe a spell for which you don't qualify and second of all you shouldn't be able to prepare a spell that doesn't fit any of your spell slots or goes above your spellcaster level.

And the way I see it the fix is fairly obvious, however, I will not comment on the simplicity of implementing something like this, because I am not an IT professional and don't wish to berate people who know how to code by claiming I can dream up better solutions than them.

Basically, you'd need to implement a warning message stating that you are about to scribe a spell you won't be able to prepare until you gain more levels in Wizard. That way you won't have to fix the actual bug which allows you to scribe anything with the Wizard tag on it.

Secondly you need a script to ensure that players don't prepare a spell for which they have no regular spell slot.