We update WP Maps Gold.
There is no other language files than US inside /lang/
There is no option about language setting inside add/manage map menu. We really try to find it.
Even if we change the general settings of the plugin, there is no change at all.
We provides only english .po file and you'll have to translate it as per your language and put it in lang folder.
though you can convert language of the map using 'Map Language' on Settings page. Let me know if you're having any problem in that.
We will translate and came back i any problems
Please let me know if any issue you found yet.