I think if you cast an evocation spell that you got from a different class, then sculpt spells doesn't work

Yeah, it took me almost 150h to finish my first playthrough, and instead of touching grass, i started a new one.

Im at the end of my durge run rn. My advice would be to not shy away from doing evil things despite what other people say about losing out on content. You really dont miss that much, and you get some pretty sweet cutscenes, especially if you commit to it. Plus, astarion and minthara will support you the entire way on your descent into darkness :)