Andrew Medeiros, Under Additional Rules for almost every PB, it says:
When you inflict an injury on another player’s character, they reduce their Trust score with your faction by 1 (on their sheet). If this brings their score to Trust -4, it resets to Trust-1 as usual, and therefore you all mark experience.
When you say “you all” are you saying everyone at the table or just the character and the character you are inflicting an injury on? If so, it may be better to say “you both mark experience.” Semantics, I know, but one that was asked of me today that I felt was a valid point.
Whenever a Trust resets from +4 or -4, the person changing it on their character sheet and all members of that faction are supposed to mar experience, but I need to review that mechanic anyway. I might simply do away with it for both healing and injury, I’m still luke-warm about it.
Your insight is a solid one though, if nothing else that change needs to be made.