I fixed it;
Looks like font files were incomplete and lines loading it lacked from fonts.dat file.
used some of the older korean patch file around 2017.
https://m.blog.naver.com/phoebe_w/220939416620Surprisingly tho, that nobody found this since like, 5+ years.
To fix it, you need to unzip Language.zip into common/Language. overwrite any conflicts, that should do.
could you integrate it into the next openxcom patch please? (I'm sure this would fix both openxcom and oxce, too)
thank you for your time.
Changes:
Font.dat
FontGeoBig_ko
FontGeoSmall_ko
FontBig_ko
FontSmall_ko