I read in your post some people who want a citizen that will move things barns to barns.
Why not a kind of store suply. Not a market but a store suply that where a citizen will collect all ressources in all barns and wharehouse and stock it in the store supply.
Yes with a radius. But the radius should work with the number of people. More people work in the store supply, bigger the radius is. Like this, we won't need multiply barns and wharehouses here and there and assing citizen to move thing between 2 or 3 barns.. Just a stock supply and more people work in, the radius will get bigger.