Since you already changed the .ini file, I suggest that you try using on-screen keyboard and you 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  !