OK, so we’re talking international keyboard handling rather than Unicode strings per se. Yes, that can be a bit creaky.
Have you tried PsychoPy’s new Keyboard class?https://www.psychopy.org/api/hardware/keyboard.html
It supersedes the event module and provides much better timing. I’m not sure if it will handle the actual returned characters any differently, but at least it is more likely that we can get changes made to the source code if required.