It’s been a while since I opened my Devterm and I don’t remember what I received for cooling, but it wasn’t what you described. I seem to remember reading about upgraded components in later shipments. (I never asked if I could get a set later on, so I guess that’s on me.) I don’t have a 3D printer, but my original plan was to get the plastic fan shield printed that someone posted but I never got around to it. Sounded like the fan shroud moved enough air through to reduce the temps to a better level. But a better heat sink might have prevented the fan from running as often too. It’s been a while but I’m pretty sure mine was going well over 71C (I remember getting into the 80s or possibly low 90s) when cranking through a build. I don’t think it was “unsafe” temperatures, but it worried me.
When I was actively using mine with the A06, I got in the habit of using it remotely, even though it was on the desk in front of me. 
I had a ssh window open with htop and eventually btop running that I would check, and adjust accordingly. But your windowing solution is cool. I had no problem using it cranked all the way down, but I felt like I could never fully use it cranked up all the way due to the heat. One day I hope to print that fan shield anyway, as it would work just as well with both the A06 and the CM4. Not sure if there were performance comparisons but I think cranked all the way down the A06 is probably friendlier with battery life than the CM4? Definitely more customizable in terms of power and battery usage, but even if less flexible, the CM4… “just works”. Funny thing is, I’m usually the type to want to tinker (PC and Android user, and not an Apple user), but in this case I guess not. Maybe I can improve the thermals and use the A06 again at some point.