Hi folks
Sorry for the being slow to answer, but we are right in the middle of working on the next update!
Cells are self-contained "pieces" so to speak, and so there is no concept of notes sustaining across to the next Cell. When play moves to the next Cell then all composing in the previous Cell stops.
If Cells have different volume levels then it is probably easiest to deal with that by using an Amplifier in the Cell FX slot (see: https://wotja.com/guide/#mix-music-fx-cell).
We do *hope* that at some point in the future we might be able to add some kind of user configurable Cell fade in/fade out (and if we are very very lucky, maybe even a way to cross-mix Cells), but for a number of reasons it is very non-trivial so not something likely to happen any time soon.
Tip: A way to get some notes going across Cells is to have a Cell in one Track that keeps playing whilst Cells in other Tracks sequence. I know it is not the same as was asked, but I hope it might help!
Best wishes
Tim