Forgive me if I’m ignorant of something, but how would it be different from Wikipedia? Crowd-sourced information, cited and reviewed by peers? It has flaws, but no more than a Lemmy community would have.

Interestingly the Merovingian dynasty wiki page does have info on coinage but doesn’t mention the barter economy you describe so you might be able to contribute there if you’ve got the sources to back it up.