Thank you for replying. My journal says "meet Halsin at Lakeshore"
I don't think Art being dead means the quest to be uncompletable. Because after I spoke with him through Speak with Dead spell, he told me about Thaniel. Then I told Halsin about this and he said to meet him at lake shore. So logically the quest progresses but in my case Halsin is just bugged and he won't go to Lake Shore. He is just chilling at camp with quest marker "go to lakeshore" on him
