It seems like eveything that struggles on the rebel side has an astromech slot, there's definitly some room for improvement through that slot.
Maaaybe, but the problems are different, if you agree that Ys, Xs, and Es all have problems. Ys are getting BTL-A4 which may open them up for non-turret play, X-wing generics are in trouble but not to the same degree E-wing generics are. It would be problematic to implement an astromech that fixed all three without breaking one or more.
Generic Astromech 3 points, when you perform a green maneuver you may take a free focus action.
You could price it aggressively at 2 points and unique, but 3 points is typically the nominal cost of free actions.
Sure it opens up the possibility of triple actions on EPT ships (I am not yet convinced triple actions are that problematic), but it can't be combined with R2-D2 or other regenerators. For the Y-wing you can now actually use Blaster Turret, for the X-wing you can focus/TL, potentially saving the focus for defence (increasing resilience), and for the E-wing, they can either BR/focus or evade/focus. For all three torpedoes becomes useable by having both TL and focus.
A generic Knave for 30 points with the astro that can focus/evade every turn would be a pretty good ship I think.