With the recent release of the Shopify Payments multi-currency feature to all eligible accounts, I've been working hard to add support for this to our Shopify apps.
Order Printer Pro, OrderlyEmails, Order Printer Templates all now support multi-currency orders automatically. No changes are needed to your templates, the amounts and currency shown will automatically update to match what your customers saw when placing their orders. Below is an example Invoice from Order Printer Pro, showing a Us Dollar (USD) based store, selling products to a customer in Japanese Yen (JPY):
OrderlyPrint will be updates shortly to support multi-currency orders as well.
You can learn more about Shopify's multi-currency feature, and how it can help you, here: https://help.shopify.com/en/manual/payments/shopify-payments/multi-currency