For some time, we have many different types of coins. Gold, Silver, Gold, Leprechaun, Ancient... I'm sure many players have a massive amount of some coins. I think these coins shouldn't be artifacts but a currency. Here's what I suggest:

The removal of all Coin artifacts and the introduction of these coins as a currency. Like diamonds, gold and in some ways, resources. I suggest a new building, called the Vault, or it could be a new tab inside the Storehouse. In this new building, or new tab, the window would simply list the different type of coins, and the amount we have of each coins.

These coins would still be used exactly as they are used right now, but they would no longer take a lot of room in the cities and that would make artifact management much easier for players.

I think a similar system would also work for the crafting ingredients.