Hi 24! 
Nope. It doesn’t. As I said, Nuendo doesn’t react to the MCS faders at all, the MIDI interface however does. Other apps will also react to the MCS faders, I just tried this out. But the CC#'s still tally with the XML of the settings I exported when it still DID work.
Nope. Never used QC in Nuendo. In Cubase, yes, but not in Nuendo. But thanks for your help, and I will check out if I do maybe have QCs mapped that I didn’t know/forgot about…