Hi There Pizzasarfari!Mediator is definitely shoving us into a box that we might not fit into, but I understand why we're given the name peacemaker. It's a bit of a nebulous word and different interpretations of the word fit different 9s.
Think of it as meaning we make 'peace' as a general concept. We want peace, we strive for peace. Peace of mind, peaceful life, peaceful interactions and personal relations with other people. We make peace for ourselves. The idea of being a bringer of peace between other people can also be true of some of us, particularly So-focusing 9s, but definitely not all of us.
Still falls under the category of peace seeking.I think "peacemaker" as a concept for 9s is mostly for So dom 9s as So dom 9s seek outer harmony unlike the more inner harmony focused Sp 9s or the more melding Sx 9s. So 9s are like those people who like try and keep the peace in groups and will proactively take action to ensure peace while a Sp 9 will more likely withdraw to ensure inner peace while Sx 9s meld with others to get that fear of separation away.
Its like we get three animals the So 9 is the parrot trying to get everyone to get along via diplomacy while the Sp 9 is the snail retreating into his snail for comfort and peace and the Sx 9 is the chameleon who merges with their environment. Id say So 9 is the "Peacemaker", the Sp 9 the "Stabillty maker" and Sx 9 the "Energy medatior".