Minor update: Su-su now is first to enter the coop at dusk, waits patiently for me to lift her up onto the perch, and then she growls her orders to the chicks to join her, which they readily obey.
I generally hang around outside listening for disruptions which are very few. Night before a chick lost her grip on the perch and fell off, and by default she was heading for the old sleeping corner on the floor. I rescued her and put her back on the perch where she remained.
Despite their tardiness at getting around to roosting, this has been the easiest chicks ever to perch train, no doubt thanks to Su-su being in completely control of the brood.
I'm learning broody vocabulary. It's more complex than just tid-bitting. It seems the broody "growl" is more than hormonally based irritability. There's the basic growl that calls the chicks to her. Then there's the excitable growl when I show her the meal worms. That growl is combined with rapid tidbitting and the growl sort of ends in a brief scream.
Chicken-speak as a foreign language. I can't speak it, but I have no trouble understanding it.