The idea of "levels" of resistance is incorrect. You either have it or you don't. Multiple sources can improve resistance, and are necessary for the tower, but otherwise there are no different types of the same resistance.
Anyway, I do hope at some point TB will do some very minor, purely bug-fixing update of ADOM just to resolve a couple of the main issues in that list. Whilst ADOM is very stable and the problems aren't game-breaking, it would be nice to consider it completed with some of these issues ironed out before JADE takes over completely.