- Set environment variable LINGUAS="kk"
- Try to configure, compile and install thunar-volman:

Making all in po
make[2]: Entering directory `/var/tmp/portage/xfce-extra/thunar-volman-0.5.2/work/thunar-volman-0.5.2/po'
make[2]: *** No rule to make target `kk.gmo', needed by `all-yes'.  Stop.
make[2]: Leaving directory `/var/tmp/portage/xfce-extra/thunar-volman-0.5.2/work/thunar-volman-0.5.2/po'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/var/tmp/portage/xfce-extra/thunar-volman-0.5.2/work/thunar-volman-0.5.2'
make: *** [all] Error 2
emake failed

ssuominen@unique /tmp/thunar-volman-0.5.2 $ ls po/kk*
ls: cannot access po/kk*: No such file or directory

$ grep kk configure.in 
XDT_I18N([ar ast ca cs da de el en_GB es eu fi fr gl hu id it ja kk lv nb nl pl pt_BR pt ru sk sq sv tr ug uk ur_PK ur zh_CN zh_TW ])            ^^ <-here

There could be other languages, this is just the one we found:

https://bugs.gentoo.org/344651