I couldn't even get the editor to work, that's why I didn't mention 3d assets. Of course, full 3d import-export would be great.
Norbyte's Contraption is what you need for that: it also contains a utility to convert meshes between Granny 2 and an actually usable format. It'd be demanding too much to say "oi! Norbyte!" but y'know. Maybe.