The application is shipped with the support for ENGLISH and GERMAN. Any other language might be easily added by providing a localized ApplicationResources_$$.properties resource bundle placed beneath $WEBAPP/WEB-INF/classes/de/jcon/jproject/resources where $$ stands for the language code.
Change the property.languages property of the setup file to enable your language for the application.
You can even specify country specific languages, e.g. en_US, en_UK.