Language
From OpenKM Documentation
Adding new language translations, create your own or simply modify what comes by default it so easy with OpenKM.
Add new language
Then make a click new language icon
And simply fill the data with your international language code, if you don't know which is yours, take a look here http://www.i18nguy.com/unicode/language-identifiers.html to find you language code.
Image icon should be 16x11 pixels take a look on http://www.famfamfam.com/lab/icons/silk/
Edit a language
Then make a click edit language icon
Edit translation
Then make a click edit translation icon