Probably this will be seen as far fetched..., but!
Something that would be really nice, is a tab in Statistics with all Marketplaces from Island.
Now you can find an Island Empty by accident on a product.
What would be nice though, is seeing all island markets and the current stock of that island next to it, with a delta column next to it.
Now when having a lot of cities, managing the big picture is very hard.
Especially when a lot of festivals hit.
As you see all my tiers are very happy.
I just moved about 8000 artisans from two cities to another city, which was a big strain on Fish, Schnapps, Rum, Canned Food, Sewing Machines and Sausages.
My depot was simply empty, but you are managing in the dark, since you have no global view on the stock.
Sewing machines are simply empty
Found a small configuration error in my hub-spoke system, now that is fixed, sewing machines are coming back up;
A global market dashboard would have caught that much earlier.