Firstly, as this is for the PC version's bugs, I've moved this to troubleshooting.
My FF7: Plus patch will resolve *some* issues, specifically:
* MDef issue
* AI problems
* Mis-spellings
I say it's mine, but it's based on other people's research. Gemini, for instance, was kind enough to show us how to change the MDef routines and find an appropriate codecave in some unused strings. El Nino provided a strong case to show that Ruby's AI is glitched.
If anyone else is prepared to show us how to fix the DP glitch and W-Item issue, I'd be very interested.
As for darkness, I did kick around the idea of just implementing an AI script that gives any blind enemy the fury status. Players wouldn't notice because you can't give hypers / tranqs. to enemies without exploiting confusion (a really obscure trick). But it's not quite the same thing, and it falls apart if the user applies certain mods.