You don't do diplomacy with anyone but the highest ranking member of a clan or the member titled to diplomacy. All other talk is between soldiers who know more or less whats going on. You said the details were hammered out to the higher ups but it seems the information has not properly trickled down and so we the soldiers talk and spread rumors. If an officer of Remnant, Hospitaller, or Astralis steps out of line it is the job of the higher ranking officer to reprimand him and, hopefully, explain the situation to avoid any future problems. If there is no accountability from anybody that is how a bad situation escalates into a worse one.
If that knight who attacked SHIK was out of line I hope his leaders have punished him, I hope that SHIK who attacked Mazen under a neutral flag is punished if he was out of line, and I hope myself and mancen get punished if we step out of line. Without the rules and guidelines to keep order why even pretend there is diplomacy?