I think there's three parts to discuss:
1. Getting the triggering timeline name: This can be done for timeline actions right now! Check out the
timelineName property of the event passed into the function.
2. Listing all timelines for the scene/symbol: As @MarkHunte mentioned, there's not really any way to know a specific timeline for the or element/scene actions as multiple timelines could be running. However, we would like to provide a way to see all timelines, then you could inspect their state and playhead positions with our current APIs.