On the mutations page the piercing cold mutation shows a damage of ~4000 for frozen enemies that don't fall and die. But I usually only get 400 damage, is this a glitch or intentional because of enemy resistance? Because I was under the impression it would do ridiculous amounts of damage.

Weak foes will be frozen to pieces, while stronge ones will only be slightly affected. Do not have any numbers for you, but it really depends on what kind of monster or human you attack with piercing cold (just like any other attack will behave).

Yes I know that but for the mutation it's says that enemies that don't shatter should take around 4000 damage, but when I hit enemies with it, it usually does ~400 that's 10 times less damage than what's stated. Even if enemies have armour and other resistances it's seems a little much to be doing 10 times less damage.

Well I understand what you mean, but - the reason why I said that I do not have any numbers simply is that I adjustet the HUD in a way that I only see the absolute minimum on "information" about any foe.

And (I guess this would be so in real life) surely some are harder to kill then others, so I just keep killing them as long as it takes to see them dead. No book keeping from my side, and I do not really expect to have any monster breaking down just because of me/Geralt being near.