The reason vertical waveforms were suggested were simply so that they could be in the same view. There's nothing super special about vertical waveforms, but Renoise tracks run vertical therefore audio tracks would have to. It's not about having merit, it's just the way it would have to be.
Redux is great but it is still just an instrument plugin. If you want to sequence a whole song tracker style it's way better to use Renoise.
Rendering stems out of Renoise and then doing your audio track recording is completely counter to the creative process.
The best option right now is to just use Rewire. There are downsides to that as well though. I personally don't want anything super fancy, just the ability to create an audio track and record into it. A simple thing that would make a massive difference in workflow.
Renoise Tracks run vertical, therefore automation envelopes would have to be.......oh wait
If you want to sequence a whole song, tracker style, remind me, why do you need audio tracks ?
Rendering stems is counter to the creative process, what planet you been on for the last twenty years, we have all been doing that for various and sundry for a long time.
You don't want anything fancy, just vertical waveforms from audio tracks in a tracker, yep a simple thing.