The non-sleeper CX 343s are NOT leased from Air China. All three of the leased Air China aircraft were returned and all fifteen A340s in CX's fleet are in CX configuration with CX seats.
As I understand, the 34Cs (sleepers) are: HXA, HXB, HXE, HXF, HXI, HXL, HXM, HXN, HXO.
The 343s (no sleepers) are: HXC, HXD, HXG, HXH, HXJ, HXK.
It would appear that priority for 34C deployment would be given to Auckland and Toronto (and I would have thought Heathrow but apparently they're getting quite a few visits from the no sleepers A340s).