The UWF WMI provider is all that Microsoft has provided for UWF, which has been that way since Windows 8 Embedded Standard. They also only provided WMI API support for Shell Launcher and Keyboard filter. I developed utilities for all three using the WMI
APO:
https://annabooks.com/SW_UWFUtility.html
https://annabooks.com/SW_SLUtility.html
https://annabooks.com/SW_KBFUtility.html
You have already written a C# with the UWF WMI commit, but I have source code example as part of my book downloads for enable and disable calls: https://annabooks.com/Book_SGWin10IoTE.html.
It might not be what you want, but you could create a C# DLL that is accessible to C++: https://stackoverflow.com/questions/13293888/how-to-call-a-c-sharp-library-from-native-c-using-c-cli-and-ijw
Sean Liming - Book Author: Starter Guide Windows 10 IoT Enterprise - www.annabooks.com / www.seanliming.com