Hi, i have done this recently.  You need to create the information for each bank account as a text field, then you use conditional formatting on each of the text fields to change which one appears when the currency on the invoice changes based on the customer account.  That way you only need to have one invoice setup.

 We use 3 different currencies GBP, Euro & Dollar and have different bank accounts for payments.  Decide which invoice layout you are going to use, save one as GBP, save one as EURO and so on for whatever currencies you use.  On my GBP Invoice I have the GBP bank details and each of the others have the corresponding bank details for that currency. 

It is possible to report on multiple bank accounts and currencies but would need more specifics on what you are trying to achieve to be able to help