Question

Do the damage converter imbuements apply on damage from charms?

For example, if I have wound against a given creature and I have imbued my weapon with powerful frost , would half the damage from wound be converted into ice damage against that creature if wound triggers?

Answer 1

No, the damage will remain physical. There is no way to change the elemental damage of the charms.
So, in your case the  Wound still give physical damage.