At the risk of oversimplifying things, pre-war there were three entities (that we know of) who could issue paper notes and have them considered as good as gold: the CoGA, Charis, and the Republic of Siddarmark - especially the House of Qwentyn. Those two countries were the only ones who weren't in debt to the church, which fanned Clyntahn's innate distrust for both, although he was right about heresy in Charis but for the wrong reasons.
Every other country's coinage basically traded according to the size/weight/metal composition of the coinage, and whether any of those coins were underweight or clipped. There would be local variations, like in Desnair where they mine a great amount of gold, so a gold Desnairan mark might buy less in the capital (where rich nobles live) and more out in the countryside.
The amount of debt a country has amassed comes into play as well - note that King Rahnyld of Dohlar is heavily in debt to the CoGA, and the Dohlaran mark has lost 1/4 of its value since OAR. That was
before the ICA beat the stuffing out of its main army and turned the Gulf of Dohlar into its own bathtub, so look for the Dohlaran currency to slip even more. Still, a gold coin is a gold coin, although with no standard set of weights and measures I'm sure that newly minted Dohlaran currency isn't worth what it used to be based its metal content and weight. Since it's highly improbable that Rahnyld is ever going to be able to repay the church, the promissory notes the church has issued him have been heavily discounted, and if it weren't for the jihad paying for so much military hardware, of which Dohlar is the CoGA's best source for quality weapons, it's likely the relatively small country whose economy is heavily based on trade - or was, until those pesky Charisians showed up (or are about to) would be in a very deep recession, if not a depression right now.
Desnair is about to take a very heavy hit, since it will soon be cut off by land and sea from all of its northern trading partners, and the CoGA within its borders doesn't have the ability to make loans that wouldn't trade at a major discount to face value, since the CoGA is losing the war. The major defensive port of Iythria, which received a great deal of church investment is gone, and the apparent church investment in naval ordinance was reduced to producing schooners to raid Charisian convoys, but those are being destroyed along with the infrastructure to build them thanks to Merlin's "spies." The Desnairan army has just been utterly destroyed, with a heavy toll on the nobility, which will certainly have some political backlash, and should the CoGA demand that Desnair produce a new army, the Desnairan mark would likely be further debased and church paper in Desnair would trade at an even steeper discount. Inflation would be rampant, making it even more difficult to pay for Desnair to remain a factor in the land war. Stick a fork in them, they're done!
Harchong just lost control of its foundries, which is a good thing for the workers, since they'll probably be paid a reasonable salary now instead of having the funds embezzled by the bureaucracy. Since the church is paying those workers and the CoGA mark is taking a beating, it's likely that those areas of Harchong will see rising inflation, possibly faster than wages. South Harchong is about to be cut off entirely by the ICN, so look for a severe recession/depression there, since church investment will dry up and trading can only be conducted over land or by canal. No more trading with North Harchong, Dohlar, or any of the countries of the northern continent of Haven. North Harchong won't feel as great a fiscal impact, since the church will still be running its foundries, but the inability to ship goods by sea will make coal, iron ore, food, etc. more expensive, and it just lost two major trading partners. Since it doesn't have as extensive a canal network as the Temple Lands or Siddarmark or even the Border States, its trade will be heavily impacted. Again, a major recession/depression is looming.
The Temple Lands are a bit of a wild card since so much of them is made up of huge estates owned by families who are basically church dynasties. It can theoretically feed itself, although its northern location probably reduces it to one or at most two crops per year. (And two would be stretching it.) It has extensive canal networks that allow it to trade with the eastern parts of North Harchong as well as the Border States, but it lost the ability to ship its goods by sea years ago, and lost Siddarmark as a major trading partner and supplier of cheap Charisian goods in the SoS. So it's been suffering at least a mild recession for years, and its about to lose Dohlar, South Harchong, and Desnair as trading partners. Despite its efficient foundries and growing manufactories, as well as having the Temple and Zion within its borders to pay for the needed weapons and supplies for the jihad, its tithes have slipped steadily since its fortunes are so closely allied with the CoGA. Plus super rich dynastic families tend to save money rather than spend it, and the serfs who toil on the farms can't leave them and are basically slaves, so the social fabric of the country will soon feel some severe strain if it hasn't already. It's also the one enemy country that will likely be invaded, if only the region around the Temple and Zion. It's probably in a recession, but that can get worse in a hurry.
We don't know enough about the Border States to make much more than a guess as to how their economies and currencies are doing, but they relied heavily on the transport of Charisian goods into the Temple Lands for income, and that ended with the SoS. That must have dealt them a heavy blow, but they're getting lucrative church contracts for weapons and supplies, as well as being the primary route for the invasion of Siddarmark and the transport of supplies to the invading armies. I'd assume that the northern Border States which have less agriculture due to the cold climate there are suffering more than the southern ones, but their economies have slipped since the jihad and the SoS, and the CoGA is going bankrupt. They relied quite a bit on transporting goods from Siddarmark (coal especially) to the Temple Lands, and that trade is gone, although a goodly amount of it has probably been made up by supplying the troops passing through and supplying the war effort. Since that's going badly, look for their economies to slip into recession and their currencies to take a beating as the church contracts (paid with paper) run out and real coinage becomes scarce and probably debased.
Finally we have the CoGA itself, which issues its own coinage, along with a
boatload of paper over the past few years. As of MTaT it was running an 18% deficit, not including the interest owed on the money it borrowed, and it had been running a deficit for three
years. Its promissory notes are trading at well below face value, and those notes are only going to trade lower as the church continues to lose the jihad. Duchairn has taken some rather drastic measures to generate emergency cash, but some of those actions can only be done once, such as selling off church properties. Even worse, there are fewer and fewer people with deep pockets available to buy those properties, so they're going to sell at a significant discount. (The bankers in Siddarmark and Cayleb would be drooling if they could buy all that cheap real estate!)
The war may stagger to an end simply because the CoGA goes bankrupt. Once people refuse to accept church paper, even if the Inquisition makes that a terminal offense, it won't be able to supply or feed its troops in the field. How Duchairn manages to feed the MHoG will be interesting, as the MHoG is likely to be as bad a swarm of locusts where the church's finances are concerned as it will be in the unfortunate lands it passes through. When the CoGA loses the tithes from South Harchong, Desnair, Sodar, and Dohlar this year, I don't see how Duchairn can pay for the jihad no matter how he juggles the budget and bludgeons the faithful.
