When I interviewed the girl last year about the fruit, she gave me mostly good information, but with one error. Here is what I recorded from our interview:
sour, but smells good…kepel means 'fist', tangerine sized... not sold in market..fruit rolled in hands like governor plum… lots of seed…yellow fleshed…a bit sweet
It is not sour, and I think she meant not that there are many seeds, but that the proportion of seed to flesh is high. I was so happy to learn that the fruit should be rolled in the hands. I know for governor plum that knowledge makes a big difference in the taste of the fruit. I have not yet tried keppel unrolled to taste the difference.
I google translated something from Indonesian saying that the skin fights bad breath (I assume that is what "mouth deodorizer" means) but I can't imagine anyone eating the skin just as it is. My local contacts have not heard this.