Hi. The rolling release is always evolving, or updating at least 🙂
For German you need to install
libreoffice-i18n-de, then setup the environment accordingly (e.g. through KDE dialog).
It is by the way a good idea to add German language as a boot choice in multilingual livedvd, so this change should appear in the next snapshot release which is due tonight or soon, if all goes well.