Hi Boas,
Our controls works with culture using the below code. It respects the culture when you set the culture in App.cs as mentioned below. But it does not respect the system culture. We are working on it right now to find a solution.
[C#]
Windows.Globalization.ApplicationLanguages.PrimaryLanguageOverride ="de-DE";
We have prepared a sample based on your requirement and we have attached the sample for your reference.
[Sample]: http://www.syncfusion.com/downloads/Support/DirectTrac/General/DatePickerdemo-644206227.zip
Please let us know if you have any concerns.
Regards,
Karthikeyan.