[arcticbull]

Currency roughly speaking doesn't move across borders, correspondent banks in each country have a ledger, you send money by decrementing the ledger on the send side and incrementing it on the receiver side. Someone else does the opposite. The exchange rate is set such that the ledger balance tends around 0.

No new currency needed.

[bt3]

I have no experience here, so I understand this in theory, but in practice, banks would somewhat indefinitely have some digital sum of a range of currencies in which they may not wish to have exposure to. How do you solve for that as a bank?

[arcticbull]

I suspect they directly trade the major currency pairs, and trade via USD for minor pairs.