Is it worth to do master in professional accounting?

1. I think graduating at 26.5 yrs old is not too late, provided that you are on track to your desired career path
2. If you can afford to study full time in Sydney, do it. At least for company law and taxation (Australia context), it is easier to pick up when you are there. It would be better if you can work in Australia after study.
3. Do note it is not so easy to obtain your CPAA now: see the requirements:
http://www.cpaaustralia.com.au/cps/rde/xchg/SID-3F57FEDE-28BEA401/cpa/hs.xsl/801_7575_ENA_HTML.htm
4. HKICPA and CPA Australia
Go to www.hkicpa.org.hk to find out the path to become a cpa in HK after your CPAA qualification. You still need to take HK law and HK tax in the transition.
5. After all, if you do not plan to immigrate to Australia, my advice is you study for a bridging course in HK and go up the HKICPA path. Don't waste money for Australia qualification. Anyway, it is your choice.

If your objective is only to become an accuntant ASAP, you are correct to pick the Australian as it is eastest. But you can just do it remotely in HK studying part time course; no need to quit your job and spend $$$ to fly yourself there. Also you need not to study a master degree for an accountant status. There are many distance learning couses here in HK gearing you directly to the quallification.

It is not too old to qualify yourself even in the age of 30. But you should be aware that the Australian qualification values less than the ACCA one on job seeking as well as salary package. It is your price to pay getting the qualification fastest.