Does SECockpit work in German (or any other language)?

Yes, SECockpit works in all languages supported by Google. When selecting a language and location, SECockpit will use that for the Keyword Search Volume information as well as the Google Top 10 Results.

The user interface is currently available in German and English. The preferred language can be selected in SECockpit under "My Settings" respectively "Meine Einstellungen".