Great success! 
I appreciate how you pounded at the problem until it got fixed 
You are right, unfortunately the map does not work remotely. It can be made to work, but it will require to move some of the processing from the browser to the Hub (thus draining valuable resources) and quite a lot of code changes... not sure it's worth the effort.
If you read a bit up, @kahn-hubitat thinks that these "Unknown" nodes are removed or re-paired devices. He found out that you can clear them out if you reboot the devices that reported them.
When I'll get a bit of time, I intend to remove and re-pair some devices in my mesh and see if I can create new "Unknowns".
Nice! this made me laugh 
You are right.
Might help folks looking for weak spots in their Zigbee mesh, but lack the ability to view things in space (like me).
Might also help folks show off their Zigbee maps and win the prize on this thread: Show your Zigbee or Z-Wave maps
