I don't know what environmental condition this tree is looking for, but if you grew up anywhere near Zamboanga, you've SHOULD also know what this tree/fruit is.
In Zamboanga, we call it Kamias or sometimes Kamias redondo, to differentiate it from its elongated cousin. The one we usually use for paksiw. But this one is eaten out of hand or as a snack, I do usually with sugar sweetened soy sauce. If you've tried it, my method for eating it is bite half, then dip the bitten part into the sawsawan, take out the pit from the remaining part and dip again. It's really sour and because it's juicier than green mangoes, the sourness stays on longer. But do you know what they're called in English?
They're called Tahitian Gooseberries. Sosyal! Hahaha