I have found this in the API docs which seems to get me pretty close:
https://www.fmod.com/docs/2.02/api/studio-api-eventinstance.html#fmod_studio_event_property_maximum_distance
And it looks like I can loop through all loaded banks and all events to get the instances that are playing:
I’m going to set that up for now but still holding out that there’s a simpler solution. Would love to hear a response if there is 