Current AL does not allow, for example, FabFilters on an audio track to receive MIDI directly, except CH1-CC1. If I wanted a ProQ on an audio track to learn my BCR2000, I'd need to create a MIDI track and route it to the audio track to transmit the MIDI signal.
If the ProQ then learned the BCR's knobs, I still couldn't use that assignment to operate ProQ without the MIDI track, because the audio track would receive only CH1-CC1.
What's more, despite this extra MIDI track to bridge the transmission, only the first plugin on the audio track would receive the transmitted MIDI. If I had a ProL after the ProQ, ProL wouldn't receive MIDI from BCR, even if I then changed the MIDI track's routing to that specific instance of ProL.
I wish audio tracks could receive MIDI in the same way MIDI tracks do.