Comment # 1 on bug 900849 from Bernhard Wiedemann

The other 3 xdg-su bugs are very unrelated

I can not reproduce this here.
are you sure you have installed yast2-trans-cs ?

note that
xdg-su -c "env LANG=cs_CZ.utf8 /sbin/yast2"
sets the environment after xdg-su, so the problem can not be in it.