I have killed the goblin leaders and looted all dead goblins. Then I returned to the druid grove.
I see the scene where the tieflings thank me that I have killed the goblins.
During this scene, two lines of his talk were not voiced.
After this scene where I accepted their gift, my inventory looks like this. (see image)
Closing and opening the inventory did not help.
Going to a merchant solves the problem for those chars who were involved in trading (you selected them in the shop screen so they could buy/sell stuff)
The shop did nothing for chars who were not selected during shopping.