We more than likely know where it came from. The Pentagon seemed quick to confirm it was indeed Russian, so I assume they do.
I could be wrong, but SBIRS, at least historically was only able to track ballistic missiles. These missiles that landed in Poland were allegedly cruise missiles, which would fly substantially lower and slower, and be much smaller. They also wouldn’t have the same infrared signature after launch as they’d be powered in flight with a jet engine rather than a rocket. I would not be surprised however if we have some space-based system to track cruise missiles.
If such a system does not exist, or in addition to it if it does, I would imagine our E-3 AWACS would have an eye on them. The internet says they have a range is ~250miles but I think it’s fair to assume it’s likely much greater than that. Otherwise on the Polish side of things they probably wouldn’t be gathering much of info. The F-35 is marked as having a 300mi range on it’s radar for airborne targets and that’s a fraction of the size (granted much newer tech and AESA radar). We’re probably also receiving Ukraine’s radar information, not to mention definitely neighboring NATO partners radar. The military seems to have implied throughout the conflict we have a full view of the airspace above Ukraine (and likely into neighboring parts of Russia)
Some of these radars are so good too that they can identify the target specifically, as in what type of aircraft it is. Not sure if they can do this for individual types of cruise missiles, but again, it wouldn’t surprise me if they could.
People with military or technical experience can correct me.