the main characters are given arbitrary leadership roles that don’t suit their previous story-arcs
Lando being promoted to General in no time sticks out like a sore thumb.
Yeah. Though there was some precedent for this in TESB with Luke having the rank of commander only three years after joining the Rebels with no military training beforehand. Like, him blowing up the Death Star doubtless was cause enough to bump him up a rank or three, but still, realistically, he shouldn’t have a rank higher than petty officer.