If I’m understanding your question correctly - you have an AHDSR modulator on the intensity of a snapshot. When you start a snapshot, you want it to ramp up based on the Attack. When you stop, you want it to ramp down based on the Release. Are you asking for in the event of restarting an event that is in the middle of stopping, for the Attack to continue from where the Release has left it?
If that is the case then this is currently unsupported. Stopping an event cannot be interrupted and restarting an event instance will start it from the beginning, discarding any current parameter values and timeline positions.
What I would recommend instead is that you have the snapshot’s intensity automated by a parameter and add a seek speed onto that. This way instead of starting/stopping a snapshot instance, you can simply set the parameter value to 0 or 1 and FMOD Studio will ramp up/down as needed.