https://bugs.winehq.org/show_bug.cgi?id=53755
--- Comment #4 from mowinebugs@mail.com --- Hi, setx was added with commit 82e8d6036fd26485db32f2f88ebb7d7b4f6b2f9a
https://source.winehq.org/git/wine.git/commit/82e8d6036fd26485db32f2f88ebb7d...
Can you see if this fixed your bug?