1. This is what I found for you:
International Mail# RL212562255CN Tracking Result
Summary
Tracking number Origin Destination Status
RL212562255CN CHINA AUSTRALIA On route

History Detail
Local date/time Activity Location Remarks
25-Jul-2016 12:45 Received by Post Office 35110007
26-Jul-2016 10:33 Departure export customs FUZHOU
26-Jul-2016 10:58 Departure export customs FUZHOU
26-Jul-2016 11:07 Departure export customs FUZHOU

2. You can track also your parcel here:
http://www.track-chinapost.com/track.php?code=RL212562255CN

3. So we know from the above tracking that the parcel in On route to Australia. Now has it arrive there, if no scanning is done to the parcel we don't know. On the Australian site the Registered Airmail from China can not be track. Have you tried to call Australian Post or go to to an Australian Post Office and ask to talk to the supervisor if he could check into their system for your parcel.

4. If it's like other countries that do not disclose the tracking of China Post Register Airmail, they could still track the parcel internally because it's registered mail and they need to know all the time where is the parcel in case it get lost.

Hope this help.