Is it still working? It's activated in my mods but those damned undead are still immuned to everything...Or are mods deactivated in custom playthrough? Weird.

This is an excellent idea. Although, as you said, it does make parts of the game extremely easy. I know nothing about modding, but is there a way to replace the racial immunities with resistances instead? So poison/bleed is still weaker against undead, but isn't 100% useless? But yea, sneak attack immunity can go drown itself...