Unless anyone else has an idea, I really dont see a way around it as it is the same for receipts too as all receipts will be translated to accounting currency and posted in accounting currency. In the case of receipts, the credit card company sends amount in local currency, exchange rate and amount in home currency. And we post the delivered amount in home currency.
I dont think there is any way you can change this for advances either unfortunately.
I think even with BADI TRIP_POST_FI. or the user exit FITR0003.it may not even be achievable but you could check?
cheers
Sally