Because it's too unfair to the villagers since that'd be 2 big mistakes that both greatly disadvantaged the villagers and the narrators as neutral parties should fix it in the interest of balance when they can.
The Grey Mage lynch could be written off since he was technically a "neutral" even though he already showed villager bias by outing wolves through proxy but if this is true, then it can't be overlooked.

On that topic, the narrator would have to confirm such a mistake if it was true so on the other side of the coin, they have to deny it if it's false so either way, I don't see why the narrators are silent on the issue.