Well, Australia will fight China to the last of Indonesian Blood. I think it is what they want. And I think they will do whatever they can to get Indonesia to their side.
That's why if we talk about Australia versus China geopolitical adversary, it is depend on Indonesian political situation. Whose party can get more power in Indonesia political throne. If Indonesia fall into China embrace, Australia will face their worse nightmare. But if Indonesia fall into Australia hand, then China will be doomed.
Indonesia was American's vassal in the era of Soeharto. But after the 2nd president fall from his throne, it is hard to predict where their political position to be. Formally, Indonesia is a non block country. But secretly, who know. Some people claim that Indonesia is US ally since Soeharto era, and still US ally today. But they are actually not true enough. Because they're close to China too, and buy many Chinese weapons. Although Australia give Indonesian their old military weapons occasionally.
Plus Australia has some bad history with Indonesia, like their involvement in the independent of Timor Leste, and their support to Papua freedom movement.
But maybe because of United States military might, Indonesia can be threatened and fall into US embrace. But who know. if US can threat Indonesia, China can do that too. As far as I know, Indonesia treats both parties equally and stay in the middle. They want stay neutral as long as possible, until the situation change and they have to choose one side.