I messed up a unique random encounter and instead of trying to reset just that one specific encounter, I decided to reset all of the unique random encounters. I used these console commands:
resetquest FFEUniqueA
resetquest FFEUniqueB
resetquest FFEUniqueCondwhich had the desired effect of causing previously completed unique encounters to occur at newly discovered locations, but now I am running out of locations on the map to discover where encounters can occur. Is there any way to reset all of the exterior cell trigger zones so more encounters can occur there in already discovered locations? Not looking for a mod to solve the problem, would prefer a console command which can do the job as I'm deep in my playthrough. Starting over or adding new mods is not an option.