Very, very nice plugin!
But could you maybe add a placeholder like %peacemaker_peace% that is customizable in the config.yml?
It would simply show whether a player is in peace mode or not.
I could use it, for example, under the player’s name, so that other players can immediately see if someone is in peace mode or not.

For example:

peace_mode_enabled: "&aPeaceful"
peace_mode_disabled: "&cUnpeaceful"

This way, players would instantly know whether someone is peaceful or not