Hi Thomas,
We have provided Localization support for Calendar Control. Hence you need to override the Primary Language of the Application in its Constructor to preferred language for translating the display values.
Please find the code snippet to change the PrimaryLanguage to German,
Windows.Globalization.ApplicationLanguages.PrimaryLanguageOverride = "de-DE";
Please find the sample from the following location with the above settings,
http://www.syncfusion.com/downloads/Support/DirectTrac/General/Localization-1119106306.zip
Please let us know if you have any queries.
Regards,
Mageshyadav.M