I wanted to use the qMRMLTransformSliders widget to specify local orientation in a scriptable module. However, the two methods I need to do this are not exposed to Python. These methods are:

setCoordinateReference()
setTypeOfTransform()

There are many other unexposed methods in the widget that would also be very useful like setTitle() and setRange(). On my fork I simply added the Q_INVOKABLE macro to the declarations of each of these methods and I got the functionality I needed, but I wasn't sure whether there is a better way to handle this.