As of Patch#7, this seems to still be bugged.
For our play :
We managed to get Halsin "out" of the Goblin Camp by sneaking, then he's on a complete bug spiral. He asks always "we are in danger, we should go" whatever the situation is, we managed to have Minthara attack then sided with the Grove, he "disappeared" to come back again after the fight in a buggy spiral, the quest is in the same state than the video above, even after the party at the camp with the Tieffelings.
