Midi Designer works like a midi monitor when it receives midi.
Midi Controllers don't respond to input with output except to update your controls appearance.
So many users have asked for this feature in all different forms so stick around, maybe something can be figured out.
Id request a new SuperControl that actually responds to the message it's set to send but doesn't send it's own value, that way a new user shouldn't accidentally put his/her software and Midi Designer in an infinite loop.