BA Avios has horrible availability when redeeming for CX flights. I asked a similar question in the Flying Blue forum - it seems that award availability in J/F are almost impossible out of the Greater China region these days. Maybe the prices will come down when the frequencies increase.
Nah I don't think prices are high due to frequencies, its just demand is really up at the moment (especially from mainland). CX is operating 3 daily flights with 77W, 359 and 35K to JFK and this matches pre-covid periods in terms of frequency (precovid was all 77W though I think not sure). CX wouldn't be able to find any new slots any time soon I believe, so I don't see an increase in JFK frequency any time soon. Maybe it might increase frequency / capacity to BOS ORD or bring back EWR to help increase supply.