The file po/LINGUAS must be updated for lxappearance-obconf. The current list is:

bg
cs
de
el
en@boldquot
en_GB
en@quot
es
fa
fi
fo
fr
gl
he
hr
hu
id
it
ja
lg
lt
nb
pl
pt_BR
pt
ru
sl
sr@latin
sr
sv
te
tr
uk
vi
zh_CN
zh_TW


Besides that, although I've said that already and don't want to be picky, it's not working with the current lxappearance code.

Cheers.