We are on the same page on this. The fact is the EEZ of Natuna overlap's into the nine dash. If you read the Indonesian statements regarding this issue, the contention had always been about the surrounding waters and not Natuna island itself. The Indonesians had been pushing for the Chinese to affirm that there is no dispute with the waters. I don't believe this issue is resolved because the Chinese is purposely being silent on it.
IMHO the Indonesians need to force the issue by exercising jurisdiction within that EEZ. If China does not wish to concede it has to push back. It then effectively becomes a dispute. Until and unless there is a formal dispute, Indonesia cannot escalate this to the International Tribunal. China knows that and hence why it has been avoiding the issue entirely. I believe the only way to move forward this issue is to force China's hand on it.
Indonesia is in an awkward position where much of its EEZ is being constantly plundered by foreign fishermen, and a small proportion of those fishermen are Chinese but a larger fraction of those are actually Indonesia's closer neighbours including from the Philippines and Vietnam. Indonesia has actually made a big show of publicly blowing up confiscated fishing boats (with no one aboard of course) in the last few years.
[That btw, is an exercise of their jursdiction within their EEZ, and has ongoing for years now, not only against China]
How this relates to their relationship with China, is that I'm not sure how high on the scale of "importance" this ambiguity regarding the nine dash line and Natuna island EEZ is, for them, in a practical sense, and how much they would actually be interested in pushing for clarification on this small sized ambiguity.
Still, I would be interested in seeing how China responds if Indonesia does actually seek to clarify that the issue is surrounding the waters around Natuna island... so I am confused as to why Indonesia has not addressed it in such terms more publicly if it really is that important to them.
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Also, I'm not sure if it's correct to say China has been "avoiding the issue" as such, because it's not like they're explicitly claiming there isn't a dispute WRT the EEZ around Natuna, it is more that Indonesia seems to have yet to explicitly call out the issue to try and ascertain a Chinese response.
Overall China is just using the same doctrine of ambiguity regarding the nine dash line, not too different to how its policy in the rest of the regional dispute.