You can't get a legendary sighting if ANY county in your realm has an animal sighting ?

I was wondering why I don't hear rumors of legendary animals anymore, so I used the console for

effect = { debug_trigger_event = hunt.2510 }

and checked which conditions were missing. This made me realize that one of the conditions is

NOR = {
  has_character_flag = recent_hunt_sighting
  any_sub_realm_county = { has_variable = recent_sighting }
}

This means that if any county in your realm has the "recent_sighting" variable, this will never be true.

This condition is used in "hunt_sighting_event_trigger" which is used for "hunt_sighting_on_action" (which causes your hunt to randomly generate animal sightings at times). This, I think, the only way to generate a sighting for yourself.

It's also used for the event hunt.2510 which is where your Master of the Hunt tells you they found your mythical animal. To get the story cycle for a mythical animal, you need "start_hunt_mystical_animal_story_cycle_effect" which seems to only be used in the event hunt.4013 which seems to require the hunt to be of a legendary type already.

So, if you are hoping to run into the White Wolf / Stag / etc. during a hunt, and any vassal has an animal sighting in their part of your realm, it seems that this literally can't happen?

This would also mean that you should be a vassal or independent ruler with a small-ish realm if you want the "Ahab" achievement.