1) AI movement can't be scripted.
2) The AI gets a substantial financial bonus. Consequently, AI Epeiros is not under the same pressing fiscal burden as the Player Epeiros. When playing Epeiros, you are forced to immediately begin attacking, else wind up buried so far in debt that you have no hope of ever returning. The AI doesn't face this problem, and so can pull back or attack as it desires (why it desires, of course, is an entirely different matter known to none).

Cheers.