When SpaceAlex designed this mod he didn't want to use the module folders, he wanted everything to be within the override folder where possible. I've played multiple playthroughs of his mod and it always amazes me how much content is in it.
IIRC only Korriban, the Unknown World and the Star Forge wasn't covered by his mod. The biggest bugs were certain modules spawning the same NPCs twice or having other strange effects but it was never anything game breaking. His goal was to make K1 feel more alive by adding more NPCs in certain areas, add a better diversification of items and appearances, enhance the battles and also adding different/better choices to completing certain parts of the game.
He's also added a better hierarchy to the various factions, like the Mandalorians, Dark Jedi + the Wookies.
It certainly isn't just an appearance overhaul!
Czerka, Twileks, Armor, Commoner clothing reskins are my personal favourites. But I'd first change the unique characters, then the commoners or background NPCs in the areas like: Taris - Taris Nobles, Kashyyk - Wookies etc.
It wouldn't be difficult to make a complete overhaul of most of the games characters with what he's already released, it would require a lot of extracting and messing around with .UTC files with the KGFF tool though.