peiman: i also read the FCOM lot of times...and also studied the CBT...i agree with your concept and the one expressed in those manuals.
unrtately on my flights in the real 320 cockpits i discvered th GND CTL light remains lit even after engines start.
moreover, had two Alitalia pilots in my cockpit today and they confirmed the GND CTL light remains lit if selected to ON...they said JL actual behaviour is correct regarding that light.
regards
fil