The current situation is like this:
You → Playing notes on your…
MIDI Controller (or PC Keyboard) → Which sends MIDI note data to…
Renoise → Which sends the MIDI data to…
A MIDI VST plug-in → Which transforms the MIDI data somehow and sends it back to…
Renoise → Which simply ignores it, because it does not currently process MIDI data generated by plug-ins…
… and that’s where it fails.
So, a few things need to change before this will work. Renoise needs to process the MIDI data generated by the plug-in as if it were normal data that came directly from your real MIDI controller.
Here are a few other threads for reference, where people discuss various tricks and workarounds: (there are many, many more threads if you search)
https://forum.renoise.com/t/plans-for-midi-routing/26482
https://forum.renoise.com/t/midi-vsts/24622
https://forum.renoise.com/t/midi-routing/24102