I say sure, why not? Even more so if it's merely in the same way that the sultans of Ternate claimed nominal influence over Sulawesi, Ambon, Seram and Papua IOTL. There are plenty of lucrative commodities to be had, if they go to the right places. For instance, Myristica globosa, aka Queensland nutmeg, seems like a plausible colonial cash crop for the Ternate sultanate and for the distribution of settlements that we see on your map, as do the various Australian sandalwood Santalum species. Australian Eleocarpus trees could also be highly lucrative in producing exotic, semi-precious rudrakshas for export to the Indian market, with the rudrakshas from the Blue Marble Tree easily dwarfing and outshining those produced by the Indian ganitrus species. And both Eucalyptol and Citral (the latter predominantly from Lemon Myrtle trees) could be just as lucrative an export commodity as Camphor was for the Srivijayans. BTW, what timeframe are you colonizing Australia in? What year did you start your colonization of Australia, and what year CE is that ethnic map from in your TL?