There are no unique Creatures that can be found only when the Chyllfroest event is active, so I don't really think it's worth it to wait for the event to happen to go farming charm points, most of the creatures that appear on the island can be found around tibia (mainly Svargrond) with bigger respawn where getting the bestiary done would be fastest/easier.
Anyways, here is a list of all the creatures you can kill during the Chyllfroest event:
Killing all of them (assuming you are extremely lucky and get to kill the 5 Yetis to complete the bestiary) can get you a total of 570 Charm points.