In FMOD Studio you can identify buses containing a resonance audio listener by running a query in the Mixer search bar. Typing #query:(Plugin.identifier == "Resonance Audio Listener") will filter all the buses containing a Resonance Audio Listener. For example, in this project the Resonance Audio Listener is on the SFX and VO buses:
Running the query returns all buses containing the a Resonance Audio Listener:
Copying the path for either of these buses will put bus:/SFX or bus:/VO in your clipboard respectively.
In Unity, to determine if a bus contains a plugin instance is less straightforward. You would need to perform a linear search from the master bus and down to any child buses for any instances of the “Resonance Audio Listener” dsp. Here is a basic example of how you do this on an event instance which should be a good starting point.