Jolly nice thread !! Second Indonesian appears here, and thus naturally, I find the idea of a continuing Srivijayan entity intriguing, let alone one that becomes a world power
As Rex has explained, Srivijaya was a thassalocracy much like Carthaginian Empire. What's more is that it was located in the crucial point within the route of international trade. States like this always slided down due to being surrounded and attacked by nearby great/growing powers from all sides. If you want to keep Srivijaya around for a long time, you've got to do something with that recurring pattern, that has always applied to historical empires that lied on a crucial trade hub, including Srivijaya. So yes, keep Chola and Java down. That way, it will give Srivijaya the necessary length of period to gradually centralize over centuries.
As for Australian issue though, I kinda understand the pendatic attitude shown by several posters here. Yes the Bugis did go there but you've got to understand the background behind their visits there. Why did they go there, and
why did they start going there at the time they did ? Why and exactly when did the trepangs become an commodity that matter ? Etc.
However, I won't say that a Super Power Srivijaya will never find a good reason to occupy Australia. If nothing else, it will be for
preventing others from gaining a base there. But I kinda doubt that Srivijaya can find a reason to start paying attention there any earlier than OTL Bugis did.