[Smersh]

I think,there is an in-game list of different terrain types and what kind of cover they give or the the manual may also have this list. Its been a while since I've looked, and I've largely memorised the different terrain types.

but the discription is more: poor, good, excellent cover, then percentages and specific effects like you want.

the set back of terrain that provides good cover, like rough, and building hexes is that they also have a movement penalty.