If people are fabricating a piece of information, and information that they will need to repeat, they do not pick a date out of the air. It is human nature to use a date that has relevance to them.
For birth of baby George B L AUSTIN, 29 Oct 1870, father George William AUSTIN is the informant. Father George has come from England where birth certificates record limited information.
Unexpectably he has to give a marriage date, and Dec 1869 suits the purpose.
The purpose is to describe a child born to a mother who is not pregnant at marriage, so Dec 1869 suits.
Next time that George William AUSTIN registers a birth he is prepared, he has thought about a date...a day and month that he will have reason to remember. The year is not so important. It just needs to suit the purpose I have described.
The 22nd of January means something to George, and also to wife Clara? The B/D/M of someone?
Having given this line of thought, I notice that they departed London for Brisbane on 21 January 1870, which date would be recently significant to both George and Clara, even if out by one day.
But keep it in mind as a possibility in your research.
Can you expand on this .....what are seeing, and where?
"...The appear to have land titles there that they possibly just collected and sold on as there is a record of sale."