In the end I got 3 powerscroll from myself (as I got the looting rights also!) and 3 from justice ( I was protecting my friend) and my friend got 3.
SO I got the looting rights on baracoon because my pet received 40 damage from barracon, is this really intended or what? Thanks for testing and confirming the bug
My guess would be that your pet/you probably qualified for the top attacker list through either your "tanking" efforts or your "healing" efforts. This is in fact working as intended.
As far as working the spawn, you should only receive Wondrous Powerscrolls (+5 skills) and/or Scrolls of Transcendence from working the spawn. Only the death of the champion should produce the more powerful Powerscrolls and potential Replicas.
