Instrument track audio with hardware synth

I have some hardware synths that until now I’ve always dealt with by using an audio track with a separate midi track. I thought it might be handy to start using an instrument track for this to combine these two with the added benefit of being able to use a visual midi editor (for example https://deepmind-12-vst-editor.jimdofree.com/) for controlling my synths, but I cannot figure out how to configure my audio return bus.

I have my instrument track working, I can actually control my Deepmind from within Cubase. I have a different MIDI device setup to be able to play the hardware synth and if I add a separate audio channel set to the output buses of the Deepmind I can hear the output properly. I would’ve expected to be able to select outputs in the VSTi Track Instrument at the right side, but this is greyed out. Within the VST editor I don’t seem to be able to select outputs for the synth either.

So now I’m left with two questions:

  1. Should I be able to select the output buses from the visual midi editor to be able to get the synth audio into Cubase?
  2. If that’s not possible, would I be able to achieve the same using the External Instruments feature, including the use of the visual midi editor?

My main goal is to simplify my use of hardware synths and ideally store my patch settings inside of my cubase projects as well so I don’t have to deal with maintaining synth patch numbers inside Cubase anymore.