Regarding A-26 rear gunner. Watching a lot of AI-against-AI (aces) hints that upper gunner and rear gunner behave differently. Upper gunner likes to fire forward and often prefer to fire not at dangerous enemy behind but at other directions.
He also likes to fire at any direction into empty place (or maybe at enemy far-far-away). Rear gunner (like B-25) behaves better. It would be nice to make behaviour of the A-26 rear gunner as "the rear", as his primary mission is to defend A-26 from behind. Otherwise it will be of a little help (for example P-61B turret's gunner is poor in defending his aircraft despite having powerful weapon).
Of course I am not sure that it is possible. For example a gunner logic may not taking into account the level of danger from enemy planes. Anyway it would be interesting to know...
Thank you for doing A-26!