1/ AI doesn't know how much TUs your units have and how far can they go... knowing it (without mind probe) would be cheating
Fair enough, they could make a reasonable assumption by taking (minTU+maxTU)/2 using the stats for the class. But overall I don't think it would be a huge impact.
2a/ aliens can't "hulldown"
Everyone can hulldown on hills by walking to the spot where they can just barely peek over the hill to shoot at an enemy. Even tanks, which cannot crouch. That is why it is called hulldown. This is VERY effective cover, in a good position maybe 40% of shots hit the hill. I would like to be able to teleport enemies in debug mode to test exactly how effective this is though, any way to do that?
Probably the most reasonable counterargument to adding this is that even with the current code the AI is still more likely to enter a "hulldown" position with the rational that
some of the enemies are totally obstructed, which is better than no enemies being obstructed.
2b/ "light cover" is (for practical purposes) no cover in xcom
Correct, except as outlined by 2a above. But I could implement it by making spread non-binary. Doing that would be an easy way to allow modders to add balance light cover, which I see as a huge improvement. However it's pointless if the AI doesn't understand it, hence one of the motivations for this thread.
Instead of adding spread, it could also take a less "realistic" approach like XCOM2 where shooting through a space with cover (even if not hitting the cover) gives a flat accuracy reduction. But that's somewhat besides the point.