Ok so I had a very strange situation occur in the last comp stomp I played. I'll try to break it down by color and faction to keep it simple. 

I am rebel advent and so is my ally Red. Red is having fun doing what the AI does best right now spamming caps and getting a Titan out. Problem is, blue who is a TEC loyalist has spread culture and taken bases very close to red. Red loses some planets to culture including his starting Terran planet (which had his only capital ship factory). Now red is logistically capped out on his other planets so he can neither build culture structures to retake his planets nor a capital ship factory to keep doing the only thing he knows how. 

So I eventually come in and get rid of Blue and move on assuming the culture will settle and Red will retake his territory. Unfortunately, Green (who is a loyalist advent) has the research that spread culture without culture structures and culture spread maxxed. Green's culture starts spreading on the neutralized planets I left behind robbing Red of the opportunity to retake his planets. 

Again, Red is pigeon-holed into doing nothing so I come in with my full capacity capital ship fleet and titan. Even though I should have way more than enough repulsion, green's culture is still winning and Red is becoming increasingly outmatched in combat. The only way I was able to save him from losing all planets to culture was to spam deliverance engine shots at his former planets to get rid of green's influence. 

As for what I'm not sure are bugs:

1. I haven't read the description of the tech, but culture spread on neutrals doesn't seem right. I thought it's main use was to spread culture on owned planets without the need for the culture structures.

2. Even when red had the ability (and a essentially unlimited resources), he refused to make anything but caps even when he couldn't use his capital ship factory. I know this is still expected behavior but the AI should at least figure out how to use what it has instead of just twiddling it's thumbs until it dies. 

3. When I fired the deliverance engine, it gave me an incorrect error. There was a planet I tried to fire at that I did not have vision of and it gave me the error that you can't fire at planets without population (which is wrong because that's how I freed up my ally's uncolonized pop planets in the first place.