As demonstrated here:
https://youtu.be/dupIap_9crY?t=345Seems to be an undersight of Johannus. I believe, along with Thomas, such an LED could be activated by Hauptwerk to indicate a stop being "LiVE". Just not sure of the mechanism needed to have the display module itself activate a switch as in hand registering or setting u a combination action.
Kinda far out, but there are capacitive switching systems that can activate a circuit by means of touching a metal "plate" such as a metal bezel, maybe? Everything, tho, has it's appropriate cost.
OTOH, moving drawknobs or stop tabs (SAMs) would solve the issue as to which stop is "LiVE" with the stop indication via the LED mini display. Kinda as in ultimate, maybe?
It appears the stop changes on the mini displays change sequentially?
Rgds,
Ed