Hi,
As also discussed in this thread, creating a scatterer event with each voice panned randomly is not possible without using a complicated workaround. Adding a pan parameter to the Scatterer Instrument would be a much cleaner solution. Besides, the pan parameter fits perfectly to the concept of a scatterer instrument, and it feels like an omission not having pan included in it (or possibly a technical limitation?).
Example: Rain drop sounds panned randomly.