Hi,
Next version of HikaShop will store the original currency information in each order.
That way, it will be easy to display both the total amount in the currency that the customer paid and the total amount with the main currency of the shop which will be converted based on the currency information (and rate) of the time of the order.
It will just be a matter of adding a few lines of code to the orders listing.
However, note that next version won't be before 2 months as we just released the 2.4.0 recently.