All resources should be infinite
I get that there are different paces at which the game can be played. Some people will like to build up as fast as possible to beat von Noisybear, while others might want to focus on building up their town, either for super efficiency, or super prettiness, or super historical accuracy, whatever. But at the moment, the resources don't really feel as though they work that way.
I think that resources should be separated more explicitly into animal/plant, and mineral. When you roll a new region, you should be pulling from two different pools.
One pool would be berries, fish, animals and soil. You should get 3 out of 4 of those, and one should be "rich" which in this sense would be what we already understand it to mean, it would produce more of that thing.
The second pool should be mineral, and would be salt, iron, clay and stone. You should get 3 out of 4 of these too, and these should all be infinite.
Having the mineral resources be mostly finite really hampers people who want to play their town for a long time, like 10+ years. You can't use them as a long term trade resource.
Perhaps there would need to be some form of balancing effect put in for the mineral resources, if they were all infinite. Maybe the resource area should be smaller, to guarantee only one mine/quarry could fit on it, which could then be tuned to only have a low output.
One mineral resources could be "rich", which in this context could mean "the resource area is twice as big", and thus allow two mines/quarries, which would then enable it to support a long term industry for trade and specialism, rather than just a minor trickle of resources to enable building your higher-tier buildings.
I think this could really help with opening up the later game, to enable people to carry on enjoying sticking with a save, even after they've grown tona large town and beaten the Baron?