>>5284510>how much is ten gold...oh boy... Alright, you can skip to the tl;dr for a short answer, otherwise, here we go.
So I've generally made an effort to keep things like economics out of the spotlight, because when it comes down to hard numbers of supply, demand and inflation, I'm just not knowledgeable enough to make anything close to immersive quality. I've got lore and worldbuilding that provides context for estimates, but the closer we zoom in, the more I shrug.
Even gold as a point of currency is a bit curious in setting because Gnome adepts can relatively easily locate mineral veins, right? This was one of the major reasons you wanted one on hand for your expedition to the north in search of your own source of iron. Well if we take that to mean any nation with the cooperation of Gnome could just excavate gold at rapid speeds and quantities then the value of gold drops quite a bit, right? That's strange on its own. But there is an in-setting precedent that minerals tend to most commonly and abundantly occur closer to Gnome's influence, which is to say, further south around the Teranford/Ephlesia area. Teranford uses an abundance of metallurgy compared to the other nations precisely because of this, and their natural affinity for Salamander providing the necessary flamework. This means that economically, Teranford would have been quite wealthy through sheer natural resources, before even touching on their ocean-facing nation status allowing for port to port trade with East Heaven and Ephlesia, as well as seafood and salts. Conversely, minerals are somewhat rare in La'Fiel - Rare enough that there's a cultural precedent which designates swords as being tools of luxury or status because the iron necessary to forge them compared to, say, spears or bows, is exhorbitantly priced due to lack of supply (and this has only increased after Teranford's fall, as they served as the primary exporter of such minerals).
Gold as a unit of currency would then make more sense in La'fiel as a legacy policy inherited from East Heaven, where the people who originally founded the country were in large part merchants and some disenfranchised individuals from the already established kingdom which occupies a somewhat vague powerhouse category, but given La'Fiel's general lack of said minerals, the only way they would be able to sustain such a unit of currency would have been to leverage significant trade efforts in order to import it from elsewhere, meaning their economy's health would be dependent on the continued health and willingness to trade of East Heaven (locked down) and Teranford (fallen). The moment they were cut off from that, the accessibility of new gold flowing into the nation would become stringent.
