SeatSpy doesn't cover CX. There are a bunch of other newish award availabiity services (PointsYeah, etc.) which I think do return some results for award seats on Cathay--and in some cases may allow you to see up availability alerts. But I'm pretty sure these are only for the (much lower) Cathay award availability via other One World FF programmes. Not aware of any award availability service that will allow you to set alerts for the much greater award availability that is available via Cahtay's own programme?