Region, province, territoryI might try to not give them a in universe name. Kinda like how the hex tiles in Civ or the snap placement in Age of Empires are just viewed as part of the game's structure. They're only 2 miles by 2 miles so unless they are empty, the stuff inside them will be way more prominent.
zone is kind of weird. It doesn't feel like it'd make sense in a medieval time, but it is actually a middle English word.
Speaking of the stuff inside them, I've decided to bite the bullet and go with a freely explorable full open world. Basically Divinity Original Sin 2 for a seamless area the size of Europe. This is a lot of work but could maybe save time compared to my original hierarchy system. With that system there were a lot of edge cases that I was struggling with sorting out and I'd have to absolutely nail the visual presentation of everything to make it simple for players to understand and fun for players to exist in. My jump from 2D graphics to 3D graphics had similar pros and cons so I'm hoping it works out a second time. The only thing I've really worried about is character icons. I cannot have 3D models for every person but with a higher quality world, it'd be hard to make anything else look like it belongs.
Within sectors/tiles/zones there will be "locations" for lack of a better term once again. A location could start as a single hut and grow into a massive city so I'm not sure what to call it. Locations have location wide upgrades similar to sectors. Buildings are built automatically at the closest point to the center with enough room. This way they naturally grow like real cities but I do not need a system for players/AI selecting specific building locations.