ChineseLunisolarCalendar is not available to store apps. You can make a suggestion at
https://wpdev.uservoice.com/forums/253374-missing-platform-apis but I doubt it would
be high priority.
You can port one of the existing implementations to WinRT. It is not like people do without
lunar calendars before ChineseLunisolarCalendar arrived in .Net 2.0.
Visual C++ MVP