I have a log of pictures with russian, japanese and chinese filenames.
Examples: 3d-art-красивые-картинки-art-пираты-6497178.jpeg or фото-Природа-озеро-горы-6946340.jpeg
When I rename them using the CMD shell:
ren фото-Природа-озеро-горы-6946340.jpeg 00000temp.jpeg
I can convert them and rename it back afterwards. See attached screenshot.
It does not happen für typical WESTERN unicode filenames with German Umlaut like ÖÄÜ.

That exact source picture on the internet:
http://joyreactor.cc/post/4943227

Cannot test that for *nix, don't have a linux at home any more (last was about 2015). But since the normale cmd copy / xcopy / robocopy and all other windows command line tools can handle it it should be possible for the windows version of CJXL too.

kind regards,

Joachim Otahal