They may choose to intentionally misuse long haul aircraft on regional routes
While it may look like misuse, it's actually always been a huge bonus for CX, unlike other major long haul operators CX can effectively use these aircraft between long haul flight as they've done so since the 747 first arrived. Many other airlines have to park the aircraft for long periods either at home base or an outport waiting for appropriate flight timings and have large other fleets to do the "domestic work". CX can chop and change between 275-350 seats basically as they see fit to contribute to the A330 regional work. CX has always had very high aircraft utilisation compared to the rest of the world.