Sometimes it is impossible to revert hostile conquest. For example, if a player pledged to hobbits kills orcs near Dunland, they will earn conquest inside Dunland that helps their allies, Dúnadain of the North. Dunland players cannot revert the conquest by killing the rangers, as it is hobbit conquest, and can't even revert it by (somehow) killing hobbits in the area, since Dunland isn't enemies with hobbits.
A solution to this would be changing it so that killing an enemy not only checks the enemy's faction's conquest, but also any of their ally's conquests that would spawn the killed NPC, and reverts it. In the above example, if a Dunland player killed a ranger, the mod would check Dúnadain of the North's allies and revert the Hobbit conquest.