While the act in itself was a crime and the consequences terrible for everyone, the original Forsaken actually succeeding in slaying Father Wolfis pretty impressive.
Father Wolf's story in general seems to have been full of these:
For starter, the fact he was apparently so strong he single-handedly could serve as the guardian of the Spirit World, something the Forsaken struggle to accomplish today. Granted, Pangaea probably made it easier, but still; he was able to do of his own what entire packs of his children have a hard time accomplishing.
The Hosts existing in itself is the proof of one for him. Why? Because they all were once parts of bigger, powerful mad half-spirit abominations who abused their powers... until Father Wolf got tired of their crap, tracked them down and slayed them, forcing them to leave these remains behind in the hope they would be able to come back through them. These things exist because Father Wolf easily slaughtered a much more terrifying version of them. In the Belishu's case, the defeat was so traumatic they now have a paranoid terror of Werewolves.
The fact that despite fighting a losing battle against the large majority of their own kind, being hated or distrusted by the wide majority of Spirits, and having to handle other horrors like the Hosts or the Indigam, the Forsaken still chose to stick with their decision to carry out Father Wolf's duty and redeem themselves for his murder. Even in-universe, this determination is considered impressive, as this is the main reason both the Predator Kings and the Bale Hounds see them as Worthy Opponents.