AudioProcessorListener is not notified when host changes parameter

That's because each wrapper (which is the gate between the Host and the AudioProcessor) is an AudioProcessorListener, therefore when an object that is an AudioProcessorListener calls setValue() it doesn't exactly want a callback to tell it the value has been set. Think of "setValueNotifyingHost" as actually being "setValueNotifyingListener".

I think to be honest you probablt shouldn't be using theAudioProcessorListener unless you are creating a new wrapper.