'Naff' is slang for anything bad generally speaking, synonymous with 'crap' although it is only used as an adjective.

'twee' is used to describe anything/anyone cloying, unnecessarily saccharin, effete, affected style. It's a dictionary word so you should be able to find definitions and synonyms like 'sentimental, sweet or pretty' (I would add a rider as excessively so in the mind of the beholder).

As for describing films, one person's tweeness/naffness is another person's fun/delight.

I love almost all of the Disney films when I can push some of the American mush out of the way. The more recent the film the more mushy generally speaking. Snow White and early shorts, absolute magic! Must say I thought 'Moana' was well done though.