Actually, :
8.3.5.5 Cell Balancing The device supports cell balancing by bypassing the current of each cell during charging or at rest. If the device's internal bypass is used, up to 10
mA can be bypassed and multiple cells can be bypassed at the same time. Higher cell balance current can be achieved by using an external cell balancing circuit. In external cell balancing mode, only one cell at a time can be balanced. The cell balancing algorithm determines the amount of charge needed to be bypassed to balance the capacity of all cells
there is a capability to self balance at rest.
Since as you pointed out correctly each cell can be read via log or in the app, what's the big mystery? OP can easily read per cell voltage after his device stops it at 90% and we can all know.