Have tested (briefly) on both Chrome and Firefox and works as intended as far as I can see
Only highlights nodes which makes for having to look vary carefylly to see errors - especially on Major Highways (they are red)
Only works at zoom level 100m/500 ft or closer - meaning there is still quite some scrolling to check the larger roads/routes that typically are quite long. (not sure if possible to make work at zoom levels showing larger areas.
The Country/Border function shows up on the Danish/German border but not at e.g. the Danish Swedish border separated by a 3 mile sea. Does show up where a road on a bridge connects the countries and the road changes country at one point.
I would really like it if the segments (not just junction nodes) could light up - but not sure what everyone else would prefer. Of course the segments still light up when you click on a neighbooring segment.