I can’t really judge character arcs without knowing the whole trilogy plot so i think rewriting that aspect of TFA is basically not worth doing right now, just in my own opinion.
Personally I’d be more interested in engineering a script that wasn’t juat 75% SW77 redone. Keep the characters basically the same but engineer a new plot, new events and things like that.
As a start I’d more clearly explain the whole First Order/Republic status quo. Or remove it entirely and make it clear that the Republic is really the dominant force in the galaxy. Have the First Order just basically replaced by a fractional and marginalised Imperial Remnant or something.
I would work on transitioning Finn’s defection more gradually so it’s not so jarring as well. Same perhaps with some of Rey’s elements. Basically keep the same character beats but develop them more organically.
Oh and Phasma would be the badass stormtrooper with the electrobaton.
I think explaining the First Order/Republic status quo is a little prequelish since it’s not really important to the story of the characters. The First Order should be powerful not weak.
I agree with everything else though, but there does come a point where people try so hard at being different that they forget to make a good story. Really the only change to differenciate itself from A New Hope is to remove the Starkiller Base, but then the stakes aren’t as high, so we really need to setup The First Order as incredibly strong. In that first scene, have the village completely decimated by the First Order. Setup the non-Death-Star base as impossible to infiltrate. You don’t need a superweapon to be intimidating. Look at the Empire Strikes Back! They destroy the Rebels and they lost their ultimate weapon.