On tracking the missile’s origin- no it’s not some panoptic capability that NATO possesses. There are limitations based on what sensors are active on the ground and in the air. Range and terrain from sensor to target is key too, especially for…

Low flying, terrain masking, small radar cross section, cruise missiles and drones. Just because a radar is active X miles away doesn’t mean it detected it or even had line of sight to it.

That being said, the they should still be able to piece together what this was and who it belonged to. Russian missile or errant SAM etc, which happens especially with older Soviet era stuff

Larger SAMs can travel a long way on ballistic arcs and/or gone dumb. So 1.) If it was Ukrainian and not nearby, it could have been fired from deeper in the country trying to chase down a threat even. 2.) Russia uses S-300s in the ground attack role...

and although it is somewhat unlikely here, Russia does use Belarus to fire its standoff weaponry. Also, Russia's missile stocks are in question and a SAM would be relatively inaccurate at a highly extended range.

Errant/or dumb/ballistic SAMs shots are a thing with Syria's SA-3s.
www.thedrive.com/the-war-zone/28783/errant-syrian-missile-flies-over-mediterranean-and-crashes-onto-i...