I'm curious if your mango suffers from softnose. Its reported and I've seen it with my trees that too much nitrogen fertilizer brings about softnose (jelly seed) in mango.
Too much watering also can effect the quality of fruit as well.
Obviously by the photos your tree is very healthy and growing great. Is it possible that the tree would have even more fruit on it with less care? There is no doubt mango likes and grow great in fertile conditions. But, also its known that mango like to be stressed and its best not to encourage the tree to grow too fast. Mango are very drought tolerant and in Florida we get enough rain to support them.
I've seen mango growing in old dilapidated and abandoned groves holding an overabundance of fruit. In contrast, I've seen well maintained trees not produce. I've been growing mango for 20 years and have never watered or chemically fertilized my trees and they produce great with no care. Of course, I'm just a homeowner hobbyist and I don't need too much production for it to produce enough for me. My problem now is shading, as the trees have shaded themselves out and we all know they need full sun to fruit.
I'm suggesting that maybe that you are providing too much care for your trees and that although you are getting a lot of fruit that the fruit may be inferior or has softnose.
Its an interesting discussion for me as I always tell people to never water or fertilize mango. They don't need it. But, again, I also can be wrong and there is no true absolute right or wrong on growing mango.