Hearing Lucanis talk about why the Crows aren't active in Fereldan anymore, that "House Arainai embarrassed itself so badly", I don't know if that's necessarily talking about Zevran. Some people have speculated on why the Crows are so different in this game. Lucanis says they can be picky with contracts. We find a memento, Contract: The Next Blight, which is from the Fourth Blight; meaning the Crows should have been helping with the Fifth Blight anyways. Maybe the embarrassment the House suffered wasn't Zevran's failure to kill the HoF, but moreso that House Arainai accepted a contract for the HoF, whom they would have been obligated to aid. I might be misremembering, but I feel like I got the impression that Zevran was told to take the contract because of other Crows? Like they sent him to do it, after his last mission, to "prove himself"? It's been a while... But we know afterwards if he's alive, Zevran goes to take down the Crows; he may be focusing on the Arainai House, which would also explain the "embarrassment" of them going through six Eighth Talons. That they were then brought down by one of their "failures". Or if he dies, one of the other Houses might take that responsibility, to clean out the more corrupt Crows.
EDIT: Ahhhh okay I have to add to this now, thank you so much for the hashtags and replies (and Zevran lovers!) because I'm thinking of all these things I forgot to say AND other things that have occurred (and that I looked up bc I had to go down the rabbit hole):
