The next thing I'm doing for the adjustment database is making combining characters work. Currently, only precomposed characters will be adjusted. If my understanding is correct, this would mean finding any lookups that map a character + combining character onto a glyph, then apply the appropriate adjustments to that glyph.
Right now, I'm trying to figure out what features I need to look inside to find these lookups. Should I just search all features?
After that, I'm going to tackle the tilde-flattening issue, and any other similar marks that are getting flattened.