Awesome! I had some instances of "digging so deep into a fascinating problem that I forgot the initial reason I started digging" :)

It actually looks like a reasonable system overall. Maybe a bit bloated on the node.js side (what isn't?), but I wonder if they just had that toolchain already in place/experience with it, even though it's overkill for the system as-is. Or maybe they just googled how to do networking and copy/pasted the top Stack Overflow answer that included Socket.IO.

Did you figure out what the green graph on the right of the display represents? :)

Do a follow up plan with the grafana bit. I'm intrigued