God, this mechanic is aggressively unintuitive. Why can the AI tell me this if my city is on an unsettled landmass? If the city is closer to an existing one owned by me than an existing one owned by them?
I have the outline of an idea of what a fix would look like. Maybe there'd be some unit called a Surveyor or Explorer or something, or maybe recon units would gain the ability to do it and be a little bit more relevant, but you could have them go out and leave a trail of "claimed" land for some number of hexes, and other civs would have to avoid settling on it or get hit with a low-Grievance Casus Belli. With that in mind, to keep it from being too strong, the claim would have to decay over time, like actual land claims that aren't acted upon. This decay could be faster the further it is away from one of your cities. Maybe the Casa de Contratacion could change to buff this? England could be better at it? My kingdom for anything with more depth than the 50 Diplo favor promises, at least for this.
I have the outline of an idea of what a fix would look like. Maybe there'd be some unit called a Surveyor or Explorer or something, or maybe recon units would gain the ability to do it and be a little bit more relevant, but you could have them go out and leave a trail of "claimed" land for some number of hexes, and other civs would have to avoid settling on it or get hit with a low-Grievance Casus Belli. With that in mind, to keep it from being too strong, the claim would have to decay over time, like actual land claims that aren't acted upon. This decay could be faster the further it is away from one of your cities. Maybe the Casa de Contratacion could change to buff this? England could be better at it? My kingdom for anything with more depth than the 50 Diplo favor promises, at least for this.