Is there any documentation for timeline callbacks and emitters? I suppose a further question is should I be moving away from using emitters and towards creating instances in script? There seems to be much more documentation around instances than emitters
Unfortunately, we do not currently have any documentation regarding using timeline callbacks with event emitters. Event emitters are designed to manage the lifetime of a single event instance, and are relatively constrained in the scope of functionality they provide.
If you intend to make use of timeline callbacks, I would recommend creating instances in your own scripts and using our Timeline Callbacks example as a reference. However, if you still want to make use of event emitters, you could instead modify their source at ./Assets/Plugins/FMOD/src/StudioEventEmitter.cs and add the required functionality.