If CX can't cover seasonal illness then it isn't a crew illness problem, it is a lack of pilots problem (caused by Mis-Management) to cover what naturally occurs.
They have given up on direct entry FOs and Capts - apart from the wrongly terminated returnees, they were only getting aviation misfits. The big push is to recruit and train up SOs, but this will take years.
In the short term the GMO is putting together an application to HKCAD to lift the limit to 1000 hours. They will argue that with the JCR and BAM they can manage the fatigue. Another thing on their side is the complete disconnect between fatigue and its reporting. If you take Controlled Rest file an ASR-F. If you are too tired to do a duty don't call sick, call 'unable fatigue' and file an ASR-F.
If you think 1000 hours will mean more pay, you are deluded. They will adjust the thresholds.