This list includes anything launched this year with a COSPAR ID, not just civilian launches, be it a mysterious launch from Russia/China, NROL, or the X37 you mentioned in the other thread. A lot of this is probably public, I imagine that is why we know the SATCAT numbers for Misty and other spy satellites, because it will get discovered inevitably.
In some cases, even trajectory information is discovered rapidly by amateurs, like from NROL-108
Two payloads orbited by SpaceX’s launch of NRO mission - Spaceflight Now:
amateur observers located one of the satellites within 24 hours of its launch from pad 39A at the Kennedy Space Center in Florida.
or even photographed in-orbit. At the ~8:00 in the following video, there are a few of R. Vandebergh’s pictures of a spy satellite as well as the X37 from the previous OTV-5 mission,
As far as I know, it is impossible to secretly launch a vehicle of any substantial size into orbit, so pretending a launch did not happen would just draw more attention. Maybe the US could pull it off in the Pacific, on some forgotten atoll, but transporting the payload there would take more time and be even more conspicuous.
Well that was likely unwise, Wikipedia has edit/deletion logs, so that probably just makes it more conspicuous.