Hi,
I hope I’m just missing something and this is a simple configuration issue. It seems that all order related information is stored in the primary currency only.
This means that when I update the exchange rates and a customer retrieves the details of an old order or gift certificate he sees updated amounts… This is very confusing since they know they paid for a certain amount and now the amount seems to have changed for already completed orders 
I truly hope this is just a configuration issue and somebody can help me out how to fix this.