In Star Wars lore different races have different reaction to different fractions. Like the Mon Calamari where the emporer tries to justify their enslavement and tell people that they were not sentient. Although they had made great accomplishments with space travel.

What my rambling will be about is to try to make the different species in your mod to react in a manner that makes sense in the Star Wars lore because in stead of just having some useless allies who keep spowning on the planet the planet itself likes some bonus. For exemple Kashyyyk. The wookies are very loyal to the rebellion but their plan is completely in lock down. And many wookies are getting taken away to slave encampments. So you could make some quests with the goal to liberate the planete. It doesn't become a rebel planet like usually when you are raiding a planet. But it emperial planet the building and the things that are produced on the planet will get a huge de-buff. Take from the rebels series where some rebels are sabotaging the empires war machines so that they malfunction in combat. So when the enemy empire builds a tank on Kashyyyk some of the tanks that will be produced on Kashyyyk will just break down or not fire at all. Because the wookes have sabotaged them on Kashyyyk. When you at last are gonna try to capture Kashyyyk to a rebel base instead of spawning wookies the wookies have already sabotaged some of the buildings on Kashuyyyk just like the rebel series. And if it was like an empire world then the empire could get spies who could tell you when the rebbels will stealth attack so you actually have a chance to react or some of the rebel citizens are doing like vigitalism. And sometimes just attacking random rebel bases and telling you when they are doing it. So the empire can come and scoop and take a more defenseless planet. There are of course more possibilities and I think the best inspiration is looking at some of the rebel films or whatever Star Wars lore there is, because I can not see why it is not possible to make a lore friendly mod and balanced game because you haven't shown me otherwise. Stay awesome!!!