I was thinking about the reasons for the major factions to have not adopted their own form of currencies in the time since the fall of the second empire, and am wondering why they haven't. Here's my speculations;

The Holy Nation was my first thought; Cats bear the name of Cat-Lon, the Chief founder of the second empire that enslaved, brutalized and committed genocide against the humans. Surely the descendants of their human slave force would want to come up with their own form of currency. Maybe they don't even know Cat-Lon exists? The Ashlands are extremely far from holy nation territory, and broadly speaking their citizens are not fond of reading scientific or historical books. That and most humans currently alive can't remember the atrocities of the second empire, it's been over a millennium after all.

The Shek Kingdom I can understand, they're not all that prone to building or maintaining infrastructure or complex systems. And being that they also don't remember the second empire, it's probably just a convenience to have a currency already made and available.

The United cities I'd think would want to make their own currency because they can more easily control it's value, allowing the Trader's Guild inflate/deflate it at their will, or safeguard it's value against rise or falls in the supply of it's goods, like food, water, slaves etc.

Hiver colonies probably don't care. If it's true their lifespans are shorter than even humans, then they're even less likely to mind the history of the continent and the exploitation of their ancestors by the Skeletons. They're also pretty isolated from other societies, as is their preference.

As for the skeletons, a lot of them are wracked with guilt over the treatment of humans during the first and second empire, many choosing to become thralled or resetting their memories to forget the horror. Those left would see the history of the second empire reflected in the cats, the same cats they may have used to buy human slaves 1,000 years ago, and perhaps feel the shame wash over them anew. I think the major reason they never created their own currency is because of how scattered they all are, and are the minority in every settlement their kind resides in, the one exception being black desert city which, does not have many skeletons living in it. What's most likely is they just don't have the numbers.

I'm interested in hearing anyone else's speculation!