Nylanfs
Hero
We copy the text of the spells with included math based on the character's level. And some of the errata did alter the game mechanics, I'd have to dig into my notes to remember which ones though. When it appeared that there might be a OGL for 4e I remember talking with what's his name that was in charge about it having the new SRD be an index to things in the book that would be OGC which means any errata to them would be OGC.I don't see how, unless your character generator needed to reproduce rules text word for word. It's calculations can be changed in the background just fine, and any errata that actually necessitates front end textual replication from the SRD (and replication shouldn't be critical for a decent generator) can be reworded.
As long as you know the maths and have access to the terminology, you're golden.
I also made the suggestion that the new OGL have a requirement that ALL items of OGC be labeled that way other publishers didn't have to have enormous sec. 15s and the original creators could be better credited.