On a test booking I did yesterday (using a credit card that I knew wouldn't be accepted), the reservation was made and I received a booking reference. It looks like the credit card will then be processed in Canada, as this is the reservation office that shows up on checkmytrip:

ONEWORLD INTERNET
SUITE 980 - 355 BURRARD STREET
VANCOUVER BC
V6C2G8 CANADA

Even though my first flight was ICN-HKG on CX.