This was a truly wonderful post - thanks for taking us on the fruitcation with you! Lovely idea for an anniversary trip.
I would note that based on your picture of mangosteen, and my limited experience trying the fruit, half of yours looked a bit rotted/overripe. So that might have affected the flavor. But I wrote about my experience elsewhere, it was equally underwhelming, although more creamy than citrus-y. Like a somewhat creamy lychee, but in my case with a slight metallic taste which I also didn't care for. It had sort of a complex flavor that was hard to identify, but I'm sure I didn't get the full complexity that it is capable of. I saw no evidence of resin or any problems with the fruits, and they appeared fully ripe but not overripe/slimy, but the exteriors were not exactly soft either. My assumption is that any fruit that has had that much of a trip, or was grown perhaps in poor soil, would not taste so great as fresh off the tree and ideal conditions. It's not really fair of us to consider mangosteen less than amazing if we have not tasted it in ideal conditions, because certainly any fruit that has been irradiated and shipped weeks to sit in a store would turn us off to the whole variety, like a grocery store apple or banana (or mango!). And that's not really fair to judge them by, is it? Even Coffee Arabica has dramatically different flavor as a crop based on where grown and how cared for, even when it's all the same variety. So maybe in Borneo or wherever, eating mangosteen truly is a transcendent experience. All I can say is in SFL, so far, it is not.
I would admit though, while I think the experience is certainly overrated for the price, I can't help but still consider buying more in the future, in case I finally figure out what I'm missing!
And, I continue to grow my own mangosteen tree and hope it actually fruits someday.
The trip looked amazing, and brought me new excitement to go out and see all my local SFL sites once again... because it's hard to ever get enough!