Just an idea - on the Alliance chat screen, notifications are pinged regarding any heros that an alliance member has unlocked.
A bit of a double-edged sword, but could notifications also be sent to show when an alliance member evolves or promotes a hero? Double-edged as while this could be good to show who is working on their team, it could clogg the chat screen up, so perhaps a separate alliance board that shows just this sort of information “Barracks Updates” or such like