When AI being attached by archers its not smart and can be killed by 2 single unit archers
Right now if there are two player archer units and two AI archer units the AI will chase after one archer and leave the other archer alone to pick off the AI.
If you forced the archers to dig in for one turn after they have moved before being able to shoot and put in a max effective range, that will help a lot in stopping that and making the machine AI tougher.