A Brief Encounter

I think the advice is misleading. It's trying to tell you to keep the enemy spawns far away enough not to aggro you or Murielle/ to minimize the number that do. If you have to it's easier to obtain the aggro yourself for the most part and just keep running, but Murielle's AI will itself present the problem of engaging in fights.

Their AI seems erratic. I did have that one run where Cethlenn killed Murielle. But on all my other runs over 3 characters, they just ignored each other, even when they ended up standing about 3 metres away from each other.