Yes, nested events always are asynchronous.
There’s numbers of ways to achieve that. You could:
- reroute several tracks into one “bus” track and automate only this bus track
- insert several simultaneous instruments inside the same track and automate that track volume
- use nested events as you did, but start them from the beginning, and only automate the track volume (not the instrument’s volume); however keeping long async tracks could be less robust…
Rather automate the track volume. If you want to switch from one state to another discountinously, you could have the use of the new seek modulator, though it has some limitations.
I did an experiment a few years ago, dynamically combining several kinds of instruments (sync, async, nested events…), which might interest you: Generative/procedural music experiment