I'm aware such a mod would never catch on, though like you mentioned, it would be for the best if it didn't. The direction for this mod should clear up in time, as right now, this mod's sense of direction is just beginning.
For Customs, I don't use them, but it could be fun to see what could be done.
For the former, FAF is normally controlled via MSC, but there just happens to be an Allow Interrupt command for manual FAF editing. Though if the FAF can't be reduced without it looking out of place, then I just use a Set Frame Duration. For the latter, I forgetting that all the character attributes are in one file this time around.
The changes I made to Palutena were based on the desired changes on
this particular Palutena thread, but I will revert my change to Down Throw, since I wanted to increase the hitstun of the move (it was never suggested), but it backfired.
For the glitch-related issues, I've tested every single one of my edits in-game. It's why I can't reduce the startup of her Forward and Down Smash, since her wings glitch out. If I find anything that causes a glitch, then I remove my edits to it if I can't fix it.
I'll be able to do everything except give a timer for Mewtwo's Disable, but as I've stated before, I don't want to touch any high/top tier characters until further discussion. The reactions to Diddy's changes should be more than enough of a reason.