Correct, Bubble charts at its current version is very limited, and your description is pretty accurate: calculations, sums, labels, etc. are not possible. I can’t say for sure, but I don’t expect Bubble will prioritize improving it at this point, as other plugins can solve it for you.
@exception-rambler made a plugin for AmCharts that’s worth checking out. I haven’t tested it myself, but you can read more about it in this thread: amCharts plugin [Premium now Live]