One thing that always bothered me was his use of currency. In the French original he mentions at least 5-6 types of currency and it seems they all have common sub-divisions, despite some of them being Spanish or even Italian.

Was France using other people's currrncy back then ?

The nation of France as we know it did not exist at that time and there was no standardized currency among the kingdoms that made up the crown. Livres, sous, and deniers were the standard unit of accounting but each major polity produced their own coinage. Kings also sometimes devalued their currencies to help pay for wars so traders preferred to use more stable currencies like Spanish and Dutch coins (Louis XIII did a major devaluation about a decade after the time period of the book, which colored perceptions of the time).

It was very common before nationalism and the standardization of currencies. I read primary sources about conquistadors and the contracts financing and supplying the expedition might involve a dozen currencies because each trader supplying the wood, food, animals, etc would work in their own preferred/local currency.

I'm no historian, but back then, coins were literally worth their weight in gold (or silver, copper, bronze, whatever), so it was probably easier to pay with foreign currency than we might assume...

Everyone used whatever currency was locally availible, with every merchant in border regions being very aware of conversion rates. Throughout history there was also a cronic shortage of smaller-denomination cash, stuff for normal people to buy normal things. Today, we see "clipped" coins as evidence of forgery when in fact much of that was likely related to a lack of loose change. Nobody in town able to break a gold crown? Well, maybe you buy a horse with a slice of gold from that crown.