As long as 'sans-serif' in normal in Gnome/Unity and the patch, changing language detection criteria, fixes the problem I can assume that the problem is that Qt's(KDE's) "lang" passed to font configuration xml's differs from one in GTK (Unity/Gnome).
I mean it turns out in /etc/fonts/conf.d/90-fonts-nanum.conf here:
As long as 'sans-serif' in normal in Gnome/Unity and the patch, changing language detection criteria, fixes the problem I can assume that the problem is that Qt's(KDE's) "lang" passed to font configuration xml's differs from one in GTK (Unity/Gnome).
I mean it turns out in /etc/fonts/ conf.d/ 90-fonts- nanum.conf here:
<test qual="any" name="lang" compare="contains"> string> ko</string>
<
</test>
that "lang" for cyrillic(russian) contains substring "ko". So I think that the contens of "lang" in worth debugging.