Hi Bill,
To put Garcinia Madruno sweet in some context, I will compare it with 2 similar fruits that i have eaten. First off, I have eaten achachairu side by side with Garcinia gardneriana and in short achachairu is a sour fruit whereas G. gardneriana is sweet. But on the other hand, achachairu has better flesh-to-seed ratio. Then we have Garcinia Madruno sweet in comparison. Like I said it's also a sweet fruit but I would say it's not sweeter than G. gardneriana, and G. gardneriana offers more to eat per fruit and has better flavor than Garcinia Madruno sweet.
Tomas
PS. Here is what you can do with Sweet Madruno before consuming them: