Yeah, that is interesting. And I guess it's okay. @Manbird, thanks for hauling the old girl out. Everyone else, thanks for the ideas.
I downloaded the Soundtower demo to see how they handled Osc B. And, of course, they don't. They don't account for a difference in range at all when Keyboard is turned off. They also limit most of the parameters to 120, meaning that they relied on the (incorrect) documentation rather than using an actual Prophet-5 to write their software.
My plan is to release my software (on cartridge!) accounting for this parameter as it actually behaves, and not as it may or may not have been designed. I doubt Sequential will adjust it at this point. And if they do, I'll just have to re-burn the EEPROMs!
Thanks again.