Hi,
I have a slight issue with the libratus theme. When I change the language to anything except English the only text that changes language is Login and Register.
See screenshot. http://steveluther.de/locale_error.jpg
You will see I have selected German but everything is in English except Login and Register which is in German.
This happens no matter which language I choose. All other text stays in English.
The theme is not officially included so - as will all non included stuff - all of its own custom strings are not covered by the main translation.
Either you create your own update translation file to include it or the theme author chooses to support theme based translations that are independent from the main translation. But even then someone must create such a theme translation naturally.
Specfic translations are possible for themes and plugins (I admit being lazy I didn't build in those in my own sideways plugins…).