Anytime the state or attributes (brightness is what I’m after) changes for my Fan/Light combo I call zwave.refresh_entity for the individual entities for both the fan and light. I then wait 1 sec and call it again for good measure.
The fan/light entity ALWAYS updates when a button is pressed on the switch with the last state of either the fan or light.
I looked around the web and you can either do what I did above, use z-wave polling, or trigger refreshes off the scenes (untested).