But I'm not able to go through Cathay as it's a Qantas booking.
However I cannot see where a confirmed booking can be cancelled at the whim of an operator and absolutely no mention of any compensation - for food, accommodation etc has been made. The cancellation has nothing to do with wind, equipment breakdown etc but merely to do with the whim of the airline. It was booked months ago!
Call Cathay and describe the situation. Maybe you can get them to instigate a schedule change request due to involuntary cancellation, which will be received by QF, who will then re-issue the e-ticket (i.e. a message "Your booking has changed"). (This is a similar process to say when you call the airline to reaccommodate you on another flight due to cancellation, but your ticket was booked by a travel agent). But they will likely say, of course, they can't do squat about your ticket. Given, fine.
Press them about compensation or a night's accommodation. That doesn't require touching the ticket; they don't (or shouldn't) even have to attach it to the ticket. They just need to send you the relevant documentation for the process they decide (e.g. hotel arrangements, payment in cheque, etc.)
They could very well say, sorry - no dice. So be it - you tried, but CX would suck in that regard.
To be honest, CX might be hard pressed to put you on another flight with a connection even if it were on a CX ticket, since CX doesn't have any codesharing with QF domestic flights, and moreover to that they would be unlikely to list any QF operated flights in their options (viz. if you looked for flights on the CX website, not a single one of them would have a QF flight on them).
Airlines should do the right thing by their customers and provide some form of compensation when the changes in times are great (e.g. greater than 4 hours). Unfortunately, at least in this case there is no legal forcing. This kind of change happens frequently across the world. It is a mess to resolve without legal standing, and even then. Naturally, where the plating and operating carriers are not the same, this complicates things further, even though frequently, it is the operator of the affected flight who bears the responsibility.