"Note to trainer newbie; make sure you set the trainer to run as administrator (right click on the trainer and select from menu)."
I did. None of the Witcher 2 trainers work for me. Tried all of them (those for steam), some just crashes instantly, and the "WITCHER 2, THE - ASSASSINS OF KINGS TRAINER ENHANCED ED. (STEAM 05.10)" trainer confirms the "trainer activated", same as when im ingame, every option is confirmed activated but the cheats dont work.
Gog.com version working fine here, can't speak for Steam's.