You are correct: they don't seem to honor galactic population limits, and I'm quite certain it's hardcoded that way.I just wish I could find the enemy pop restiction pieve so I could limit their fleets from getting so big, they dont appear to be limited by space colony + plant pop limits like the human player is.
And thats a bummer for me because my rig doesnt mind lagging or losing massive fps in tac battles but it will freeze or crash during the GC if enough units move at once. I suppose a smaller map with less planets may help this since it seems I'll have no way to actually limit the enemys population since I take it hardcoding isnt changable.
Or maybe I could just place outrageous prices on units I dont want the AI to spam which build quick, like fighters and such.
I do enjoy my bigger campaigns like far far away even after I remove planets I dont want either. Just trial and error, worth it though.
That or if I could get the AI to move their fleets less, which is kinda why I start them out with some pre built fleets so they dont have to move a Lot of units to assemble.