I launched the battle through the console. But I didn't expect this. You kill a stack, and two new, tougher ones appear. How do I fix this? Winning is not an option.

I lost the battle, but Khabelekh was still frozen by the Devil (they showed a video) and then "You lost."

I also noticed something: after Khabelekh's betrayal, if I was attacked, reinforcement units (various undead and demons) would appear in my battle, but if I attacked first, the enemy would have them.