Well you could use one of the “right-click” render options (render/freeze/apply FX...) on the mono tracks themselves so that they actually have mono media on them, but that’s still an extra step and not significantly better than where you are now. There can be other benefits to “flattening” these kinds of midi-generated “virtual” tracks, but kind of only in special instances.
It might be nice to have an option - maybe in region render matrix - to choose the channel count for each stem individually. That’s still not automatic, but I think better.
Ultimately, though, rendering a mono source to a stereo file just makes a dual mono file which will sound the same as it did in the project. It “wastes” some disk space, but that’s not such a big deal nowadays. Maybe you just need to take your OCD meds and leave it alone.