This is hugely simplified from a 16th century actual English system, and the English were positively rational compared to the Dutch (3 types of Dollar??) Or the Germans. Dear God, German currency is a mess.

I, personally, love flavorful currency systems. I find a decimalized currency system in a premodern setting to be an annoying quirk I tolerate because of ease of use and so I don’t antagonize other players. In my head, I presume that we are converting what we actually find into moneys of account for bookkeeping purposes.

I once worked it out in detail for an early 17th century Carribean setting. Ran to 20 pages. At the end there was a chart for how to actually do it rough and ready with a simple conversion – there was always a unit of currency that converted neatly. Or you could do everything in Spanish Pesos since that was the most common currency.