So i finally bought the smart lights and can answer my own question: No, the Alt+PgDn & Alt+PgUp shortcuts don't adjust the brightness.

This bug seems to fixed already. It's not reproducable for me at v4.111

Also do get our beta (about menu, restart). We had some code in there that would try to match your screen dimming to the lights (which wasn't supposed to be in the build yet). It is out of the beta and should be more predictable now.