Some letters in Polish language are shown incorrectly in Rhino 6:
This is a known situation that has to do with some graphics card/driver combinations not handling text well with the current display pipeline . You can try the command TestGlyphy to see if it helps until there is a more permanent solution…
You might also check if you have the most recent video card driver. Updating the driver solved this issue on one of our computers.
That works for me, thanks.