Piotr Caban (@piotr) commented about dlls/ucrtbase/tests/file.c:
fclose(f); f = _wfsopen(wpath, L"r", SH_DENYNO);
todo_wine_if(tests[i].is_todo) ok(!!f, "failed to open %s with locale %s\n", tests[i].path, tests[i].loc);
if(f) fclose(f);
fclose(f); unlink(tests[i].path);
`unlink` also needs to be changed to support UTF-8 encoding - otherwise you will fail to delete some files. Please also check `unlink` result.