Imho the AI uses especially those nations with useful but low resourcetroops well.
In my games Ctis, Yomi, Pan, Ryleh, Vanheim and Helheim are often quite strong.
I recently lost a sp game where Yomi attacked me quite early around turn 15 and i couldn't find a good countermeasure vs. the combo of swarms of archers and tough Oni demons in time
.
But i am all in all anyways happy enough with the AI, i just always set them all to impossible and imho they give me enough challenge then and i get often enough swarmed to death
.
But it would nontheless be probably cool if the AI could use standard SCs. If this feature could get exported and be modded i think it would add a lot of fun for many people.
It should be in some way modable because then modders can tweak the AI SCs for their modded nations or other mods like CB which rebalances items and SCs.