I previously did this concept for a Feitoria town center:
I think the Portuguese deserve custom art for their special town center, for sure.
The mission idea for the Spanish is great as well!
But the French suggestions don’t seem quite right yet. I think the Tannerie is maybe the way to go, there aren’t any unique markets at the moment. But what would it do? And how could it be made more specifically French?
Perhaps you could set it to automatically slowly convert one resource to another?
Otherwise maybe a unique french tavern would be cool. Call it a Cabaret, give it an Absinthe upgrade, and have the Age IV version have a red windmill on top 