Have you read this changelist from the mod description?

3.5 Classes improvements, MotB blessings and item recipes were removed for compatibility reasons and now this edition is almost exactly matches its name: SPELL fixes and improvements :-)

I've also reverted to original state some imbalanced spells like Greater Invisibility which keeps you invisible even after hostile actions which completely breaks single player campaigns as almost all enemies are unable to see through invisibility and are just beaten to death by permanently invisible player party :-)

What do you mean about "actively updating"? The last update on the original Spell Fixes NWVault page was 11 (!) years ago. It looks to me that Spell Fixes was abandoned a long time ago.

That's why I decided to publish it in Workshop myself as I think it's a really valuable mod and players should know about it.