M.cauliflora including red hybrid and M.jaboticaba are very similar with similar foliage and probably actually the same species. Coronata is also very close to sabara. White and phitrantha including scarlet have very similar leaves are are also probably the same species with some variation between varieties. Grimal is like a big leafed sabara. Trunciflora looks right on in the pic. Is Restinga a coronata as restinga just refers to the coastal vegetation type. Many other jab species have very distinctive foliage and even new growth.
I saw pretty solid differences in leaf size, thickness, bark, etc. Many clearly share lineage but the jabo species is definitely very broad when you can get compatibility with huge leaves like white and tiny ones like Coronata 3.
Dunno. I see calling them different cultivars. The differences are enough - but you're probably right that a lot of these are just genetic traits that could be all from the same original. I guess birds eating these seeds and shootin em all around in Brazil's millions of micro climates will do that to a species.