I suppose it would depend on what kind of people wound up down here... The Australian accent & vernacular is pretty much derived from working class English - both from city dwellers & farm workers - & filtered through trying to keep your mouth closed as much as possible so the flies don't get in!!

Despite the best efforts of the British, the French did colonise a lot of the South Pacific - New Caledonia, Vanuatu etc... where French is still spoken with a particular accent by the older locals

I'm thinking the Australian French accent would be kind of like New Orleans, only devolved further because of distance - & flies!!