The issue I see is that it is only possible to survive/win as the Empire because the AI is pretty bad. AI improvement is going to make it literally impossible to win with them.
For orange my issue is more that because the other AI factions leave units laying around everywhere it is really hard to find a target to raid.
Another more UX focused thing: for the green faction the unit spawning is really slow and feels unnecessary. It'd be nice if instead the infaction level was just shown on the map, but honestly I'd be perfectly fine if the units just appeared like normal reinforcements without any message.