During the credits of the movie, there was a segment listing the music used. The movie had numerous musicians work on the movie and all were credited. The soundtrack had a downloadable page where you can download some, but 3 songs that were listed "Murder of Crows", "Ultra F***", and "Dripping Taps" still haven't been found. The creator of the songs were credited to Thomas Mears (also known on the wiki page about the movie as the Thomas "Chainsaw Massacre" Mears).
The music in the movie can be categorized down to 3 categories:
1. Electronic Tracks: Mostly by Robert Benfer and created as background music (some lost, some found)
2. Hamilton Cleverdon's Tracks: Fully orchestrated tracks (all lost)
3. Independent band/musician tracks: Metal/Rock influenced songs that were independently made then used in the movie (most found, some lost)
The independent artists listed in the credits were: Man on Earth, Pram Maven, Astronaut, F.A.K.T., Dan "DjDTM" Harkin, Hamilton Cleverdon, Thomas Mears, Matt Fennell, Josh Britt, and Robert Benfer
The 3 tracks mentioned could be in category 3. While still possible it could be 1 (Since "Sneak" a once lost track was electronic by Matt Fenell and not by Robert Benfer), there are more scenes in the film have songs influenced by metal/rock that still haven't been archived compared to the electronic ones. Link to the scenes https://www.youtube.com/watch?v=AHZBYwMRtcc
On the wiki page of the film listed a section about the soundtrack, however it has some differences
On the wiki page of the film, the song "Murder of Crows" shows the length of the song, so it was found at one point, but the other 2 songs' length were "??:??:??.???". It's uncertain if the person actually did have the song, or it was an accident.
In the credits, the name was just "Thomas Mears". On the wiki page the full name was Thomas "Chainsaw Massacre" Mears
Hamilton Cleverdon was credited in the movie as "Hamilton Kleverdon" and on the wiki page
Someone named "Roxor" was credited to the song "Ultra F***" on the wiki, but on the movie's credits it was shown to be made by Thomas Mears (shown in Part 1 video of the Lost Songs below as Links)
The soundtrack's playlist (including found songs and which part in the movie that has the lost songs)
The wiki page on the movie + soundtrack
The original website you were able to download part of the soundtrack: