I think the caps are reasonable and somewhat plausible - the hotfix makes it possible to gain immunity and even healing from elemental damage temporarily through potions and spells, which is a good thing, imo. I'd say there's still room for some tuning, e.g. by increasing the duration of potions and spells outside of combat a bit (probably just increase duration of a "turn" in realtime mode). Providing different caps depending on difficulty doesn't sound too bad, either (e.g. 120% on easy, 85% on normal, 70% on hard).
