The Empire's economy resembles ancient Rome. Just instead of using gold coins as currency, they instead use a rarer titanium-based mixture for their coinage called Dex. A single Dex when traded with Humanity being more or less the equivalent to $0.54 U.S. dollars or so. Or, roughly, 1/3 an Akashic Credit.
The elves are
really lucky there is a war going on other the Akashic Pillar would curb stomp their economy. The transition to representative (and later fiat) money combined with fractional reserve banking revolutionized how economies work and allowed the explosive growth we've seen over the last century on Earth. It's pretty much impossible for a nation still utilizing commodity money to complete.
Also I think you need to reconsider the coinage value. Inflation over the last couple centuries has driven dollar value down dramatically. To put things into perspective in 1300 an English laborer could make around 480 pence per year and two dozen eggs cost 1 pence. Meanwhile today two dozen eggs costs £3.72 which if we use the historical conversion of 240 pence per pound is the equivalent of 893 pence or almost
two year's wages. Of course that conversion isn't entirely accurate since the pound hasn't remained constant over the centuries but it gives a rough idea of the price difference we're talking about.
Furthermore if you look at historical European coinages they were generally broken into three categories such as the English pound, shilling, and penny or the French livre, sou, and denier. This is the reason most fantasy games, such as D&D, use the gold, silver, and copper coin division. Historically unless you were a noble you simply aren't ever going to
see let alone use the pound/livre/gold coin equivalent.
If the Dex is supposed to be an even
rarer version of the gold coin it's relative purchasing power should be in the
thousands of dollars and there should be lesser coins underneath it for the common peasantry to use.
How you might ask? Well, they use Necromancy.
Utilizing necromantic spells to animate particularly simple golems and liches, Elves have functionally bastardized automated assembly lines and mass-smelters.
Huh. That is an interesting work around. Of course it doesn't solve the primary issue with pre-industrial societies; food production. It does mean they probably don't need to tie up between 60% and 80% of their population farming but it doesn't change that historical farms weren't very efficient.
Back in the early fourteenth century farmers produced about half a tonne of wheat or oats and about a tonne of barley per hectare of land farmed. Today we produce 8.5 tonnes of wheat, 6.4 tons of barley, or 6 tons of oats per hectare. That gives an increase in yield of between 640% and 1,700%. What's more we've had similar levels of increases in productivity across
all our agricultural areas. Potatoes, already an amazing food at 10.5 tonnes per hectare, have quadrupled in productivity and corn sextupled.
Of course having colonized over a dozen planets does mitigate this issue but to sustain their legendarily large populations I'd expect the majority of their worlds be primarily farmland.
In sheer output, they actually outstrip Earth itself, though they have nowhere near the same accuracy, or quality, that humans are capable of.
This isn't really surprising when you consider the numbers. Modern technology has dramatic improved our efficiency and productivity but ultimately Earth is only a single planet. We simply can't compete with the resources of literally
dozens of worlds. Especially when we need to actually maintain the biosphere, what with it being our only planet, while the Elves can strip-mine their colony worlds before (presumably magically) restoring the biosphere once it's depleted of all accessible resources.
