The missing tracks from 1989 were not the only ones identified on September 22nd. The "2001 Trilogy," also known as Unknown Songs #48, #49, and #50, were also ID'd through some nice detective work by members of the Primetime Music Discord community. This isn't quite as momentous as it sounds, however, because we still don't know how to access the original cuts of any of the three (the various mp3 sets (e.g., Polinsky) that have been floating around the past 10-15 years have unofficial, lower-quality versions).
It turns out the placeholder names (which came from at least one of those mp3 sets) were actually the correct names: US #48 is "Highlights," US #49 is "Pro," and US #50 is "Legends." All three were composed by Joel Beckerman, the founder of Made Music Studio (formerly Man Made Music), and Lloyd Landesman, the composer of the CBS College Football theme. All three were made specifically for ESPN, so the official cuts don't exist on a public album or streaming service AFAIK. Special thanks to Dopethrone, simtek34, RepoManFan4Lyfe, and Josh Ochs for piecing everything together for these three songs, especially Dopethrone because he found these by searching "NFL Primetime" on ASCAP (I really don't know why I didn't think of that).