I doubt that any remnant pre-Celtic populations would have much interest, Joroas.
Another likely explanation, Von Lucky, is the virtual absence of the sorts of sources of inspiration wargamers usually rely on to generate interest in a new 'period': miniatures; dedicated rules systems, or at least adaptations of suitable proxies; movies; articles; books.
In reality there are vast numbers of the latter two, but they're largely authored by academics within the confines of the disciplines of social and ethnic history with little understanding of military affairs, or the output of popular writers and local historians; very few military historians have given the subject any attention - two being John Connor and Jeffrey Grey. The current dearth of Australian colonial figures will of course be somewhat remedied by the forthcoming UK range, which will be fully supported in the hobby press with the requisite background material and rules ideas.
If you're looking for inspiration, keep an eye out early next year for the release of a local production from a young and enthusiastic Melbourne film maker on the final days of one of the most notorious 'wild colonial boys', 'Legend of Ben Hall' - initially as a short film. It's been funded through Kickstarter, and is to be released in time for the 150th anniversary of the outlaw's death in May. Once that goal has been achieved, the writer/director plans to produce a three hour epic recounting the entire Hall saga. He claims to place a high premium on historical accuracy, and has relied heavily on the advice of an expert NSW bushranger historian.