Since you already changed the .ini file, try pressing ö but if it doesn't work I suggest that you try using on-screen keyboard (a built-in virtual keyboard in Microsoft Windows OS users) and also change your Display Mode to "Borderless Window" so that switching between the game and the keyboard is way more smoother.
Also if you want a better and faster way to use cheats in the Witcher 3, you can try to download trainers. I've been using game trainers a lot after I finish the game, with trainers you can easily turn on God Mode and many more. Try searching "Witcher 3 (version of your game) mrantifun trainer". I hope that this will help, happy cheating and gaming
!