Ok... I think that for now, as a work-around, you can accomplish the virtual modules creation by comparing the manufacturer specific string, that in any case identify your fibaro hardware, so you know how many instances are to be created and associated to your fibaro rgbw widget.
Once you get this working, send the new script so I will include it in hg.
Pheraps later we'll find a solution and proper implementation of this part of the z-wave protocol.
Cheers,
g.