I am also an FO at CX and I do not even keep a HKG log book. When I was hired the HKG CAD issued me a HK ATPL on the basis of my US Flight time. As for the SOs, they have to now keep a logbook in order to get the ATP when they upgrade to FO. The US SOs that I speak with about this seem to be logging all time in the seat (not much time per flight; cannot occupy a control seat below FL200, but usually not below cruise level) as SIC in their US logbooks and P2X in the HKG log books. It is legit flight time outside of HKG and may come in handy if looking for a new job.