Does it actually make economic sense to run a cable large enough for that kind of power from Australia to Singapore? I would have guessed there must be enough domestic customers or in Indonesia that would make more sense.
Indonesia probably has enough land for its own panels.
Indonesia is ~ 17 thousand islands, many steep equatorial jungled volcanic slopes and at 275.5 million is the fourth highest population for a country globally.
Land is in tight demand with food a priority over panels and issues that may not be apparent (clear slopes leads to instability, and keeping them clear is a Sisyphean task, etc).