"Invalid QML element name" works and "valid" don't work

As an alternative to QTBUG-123535 I tried to use a Q_GADGET here. It works if I use an upper case (as I like to use enumeration names) but throws a warning that it needs to be lower case. If I use lower case (that I do not like) the warning is vanished but I cannot get it in qml anymore (in lower case, of course).

See attached example.
It will throw "qt.qml.typeregistration: Invalid QML element name "Flupp"; value type names should begin with a lowercase letter" on runtime.

If I rename it in Q_CLASSINFO("QML.Element", "flupp") in base_enum.h and Main.qml I that error:
qrc:/qt/qml/Stuff/Main.qml:9: ReferenceError: flupp is not defined

How can I avoid the warning and just use my enums upper case?