How much of the Black Knight story is actually documented?

The main issue is that several unrelated stories get assembled into a single timeline. Tesla wrote about unusual radio signals, delayed echoes were reported by other radio operators, and there were early newspaper stories about unidentified objects. None of those records, by themselves, establishes one satellite or a connection between the incidents.

The famous NASA photograph is a separate case. The object in the STS-88 images was identified as a thermal cover that had come loose during the mission. That explains the photograph, not every older claim. The leap is treating the unresolved or poorly documented parts of the older stories as evidence for the same object.

For the radio part, a delayed echo is an observation, not a measurement of a spacecraft's distance. Turning a reported delay into a huge round-trip journey assumes a particular path and cause for the signal. Those assumptions are not established just because an echo was heard.

Tesla's account is also not evidence that an extraterrestrial transmitter was confirmed. He described signals he found unusual and speculated about their origin. The stronger claims added later go beyond what that account can show.

The pre-Sputnik tracking stories are often presented as if the military had confirmed an unknown artificial satellite. Newspaper reports are not the same thing as a verified orbit or a recovered object. Without solid tracking records that connect those reports to the later claims, they are a weak foundation for the Black Knight story.

The proposed star-map reading of the echo patterns is another interpretive step, not an independently confirmed message or date. I would treat it as an interesting historical claim, not evidence of an ancient spacecraft.