I've been thinking about Maedhros's apparent inaction towards Celegorm and Curufin again. The most straightforward explanation is that he is operating from a patriarchal worldview, doesn’t consider it that much of a problem, and lets them off easily. Even so, Lúthien’s status as royalty makes it more complicated, and he is very much inspired to hope through her stealing the Silmaril, so I don’t think it makes sense for him to ignore it completely. Equally unsatisfying is a reading where he just gets really mad but doesn’t change anything. It seems there is a logic to his non-action, but what?
Possibly Maedhros isn’t really in as much control of the Fëanorian armies as it seems, and he decides that the small chance of gaining Doriath is not worth the risk of losing Himlad. You could definitely argue that it is still a failure that leads to his downfall, but imo giving him a more concrete reason makes more sense in the context of the story.
That being said, an AU where he does the opposite would be interesting. Maybe he does make a public display of punishing them but goes too far and kills Celegorm, thus fracturing the Feanorian coalition and ending in a civil war. The Oath and the Doom absolutely could drive the brothers to kill each other, and it does in an older version if I remember that right. The tears could certainly get more unnumbered