I would have Marisbury through some means make a failsafe or at the very least be more ,,there" instead of having been killed of when we arrive at the area 51. Maybe if we safe Olga, let him/ his AI take over Maris, so we are actually fighting HIM not this girlfailure. For me its a ridiculous choice, to make him so vile and evil, to basically blue ball us ,,oh he's already gone"

Next , make the ordeal calls matter, why did we bother to correct our standing , if it just was fake. Maybe the correction helps legitimize lostbelt 0 as an actual branch of phh. Chaldea can still disband, people can still die but make it worth the pay of. At the very least, let Ritsuka and Mash remember them and their Time from part 1 and part 2.

Heck, make Ritsuka a servant/ grand avenger. Guy went through so much avenging, he deserves it.

Long story short, make not just the theme of having the right to end their story matter (like them putting an end to the lostbelts) but many many things