IDWT I found the two processors you were talking about, but most of the information I get back about them is that they hold information and boost, not much "thinking" going on, hence the term "dumb" board.

It's funny, I just needed to replace one recently for selector issues. Was dropping only selector related NTSB NTST, and floor levels. Nothing else, and was intermittent. Both NP and SP processors saw the items, just CPUA was dropping them, so I was getting I/O mismatches as well. I remembered this thread, and was able to swap CWIL for an easy fix.

Leads me to believe your information about the processors on CWIL actually doing something is very accurate, but I am unsure how the interface with NP SP and CPUA would allow for the mismatches through the only CAN channel available...