Lightscreen can be translated to any language you'd like, for that, you will have to use the Qt tools provided for this task, specifically the Qt Linguist tools, it's documentation accesable here. If you wish to improve on a currently available translation, you can do so by looking through lightscreen's code.

I've packaged all of these tools and information into an integrated package for Windows, available below:

Download the Translation Package

Once you finish a translation you can send it directly to me (k39 [at] users [dot] sourceforge [dot] net).