I don’t know if this can be useful for you, but here is what I do with Groove Agent.
With GA, you can insert each Pattern used in an instrument or MIDI track. So, we arrange a partition according to our needs.
Select all events on the track, select Dissolve Part from the MIDI menu, choose Separate Pitches and OK.
You now have each drum instrument according to the assigned keyboard key. A VST will also be present for each track.
Use Render In Place and export each track as a kick, snare, hihat, toms, whatever. For me, this is easier and faster to achieve than manipulating the outputs of the VST.
Everyone has their own way, right?