Buff it so it gives the same bonus as every other emissary. And make it so that once you raise that emissary you get marked on the map.
Buff guild emissary
Guilds already struggle to keep casual player appeal. Being marked longer just makes that worse.
They are becoming more irrelevant as experienced players move away from them after finishing their guild comms. This doesn't change that because they don't often wanna be marked all the time either.
As far as reward goes it's already high in reward because people can sell at any of the outposts, which makes chances of success much much higher.
You can sell a broad range of loot at increased bonus, so it already has strengths it just depends on how you play. If you do dive to and only emissary specific missions then yes that flag is better but if just sailing to world events or fort of damned then guild will make you more gold
Could do with hourglass tweak to include towards flag commendations etc