Creature elemental resistance stacking and penetration

I wonder if monster elemental resistances work in same way as ours.
I know they do have cap on resist so they can't go immune.

Say base mob is resistant to element 75% i guess?
then its a rare with elemental resist aura giving another 50% ?
Possibly it's a map with +75% resist

Does that mean to even start doing more damage from "-Resist effects" we need to reduce the resist by 125% overcap ?

Ok its stupid to run map with resit to your element but still 50% (or more) overcap on curse immune mob ? and its one of msot common mods on rares + spawn on champs too.

This makes penetration useless where it would be required most. Yes there is yet EE most commonly used by degen builds that can't use penetration so it ends up in same spot.

I believe it (at least used to) work like this:

Monster has resist +75
Monster has aura +50 - total 125% but the cap is 75%

Player casts elemental weakness for -40, total 85% and still cap 75% : In short, the weakness had no effect.

Player has penetration 10% - cap is reduced by 10 and thus the total is 65%

Over-resist will defeat curses, but not penetration. Penetration will always have an effect.