While looking for something completely different, I came across this StackOverflow answer (https://stackoverflow.com/questions/57131654/using-utf-8-encoding-chcp-65001-in-command-prompt-windows-powershell-window/57134096#57134096). Following the first few instructions, for the first time I was able to use accented and other characters without problems.
I created a path with an accented character and Cyrillic characters and set description with Cyrillic characters. It worked perfectly.
C:\>exiftool -P -overwrite_original -description="тестове" "Y:/!temp/ccccc/h/Côte d'Azur/тестове/Test4.jpg"
1 image files updated
C:\>exiftool -g1 -a -s -description "Y:/!temp/ccccc/h/Côte d'Azur/тестове/Test4.jpg"
---- XMP-dc ----
Description : тестове
It might be Windows 10 only, though.
This looks very promising. I'll try to remember this, and add it to the faq if it proves useful.
- Phil