I find that all bonsai specimens of M. jaboticaba (sabara, most typical variety cultivated here), they don't flower or hold fruit.
The reason is lack of water, due to not enough root mass, and substrate to draw moisture from...bonsai growers don't realize, but this tree could be sat in a deep dish, like an iris, and it would evoke the jaboticaba gods to induce a flowering cycle (i believe).
Have seen the hybrid Red, fruit as a bonsai, and I assume this plant could be a high dollar item, and a welcome adornment to any office desk.