The H90 sends and receives PC messages using PC numbers 1-99 (ignoring 0). Depending on the other device, this may offset the PC numbers by 1. We plan on adding a feature to offset the numbers on the H90 to match up with other devices.
You can setup an expression pedal to transmit a CC message, and you can map a HotKnob to that same expression pedal, but you cannot map a HotKnob to transmit a CC message. It’s effectively the same thing as your example, just want to clarify that the HotKnob cannot currently be mapped to transmit a CC.