https://bugs.winehq.org/show_bug.cgi?id=51685
--- Comment #2 from Rafał Mużyło galtgendo@o2.pl --- Personally, I'm not aware of a proper open-source substitute for MS UI Gothic.
Some fonts claim to be, but it falls to the metrics - the Google/Adobe font may have the glyph coverage, but that particular Microsoft font had a certain quirk: while most CJK were fixed double-width, double-width space (U+3000) was significantly narrower.
Besides that, it is indeed a bit awkward that for many CJK apps an explicit Fonts/Substitutes entry is necessary, but that's how system font links currently are implemented.