When I switch to English (US) keyboard settings, I get the values available in the keyNamesMac dictionary of the file keyboard.py. By the way, I have a Canadian keyboard with French Canadian setting, but I’m working on PsychoPy experiments that will be used in classrooms in Switzerland (I’ll have someone there get the values of the keyboards they use if we manage to find a way to get those values).
About this not being an issue already, I must say that the older version of the keyboard in PsychoPy was allowing me to type accentuated letters on screen. I never managed to make it work on Pavlovia, though. We interacted about that here Accents in onscreen user keyboard input.