First, I have a solution based partially upon the reply. So thank you for that. But for anybody that is having the same problem, my issue wasn't exactly covered by the information.
I had seen these before and attempted to copy the CDs over again to the same results.
The computer I had been using was the only one I had that still had a CD drive, a 2010 iMac pro. It was as updated as far as it could go, but it meant that I was using an older version of iTunes. I had seen while attempting to make the initial list, the error as described above. My initial hope was that after I took the music files from the 2010 iMac and plugged them into a modern MacBook Pro, the fully updated iMusic would fix some of the errors that replacing the files had not fixed.
This did not turn out to be the case.
The solution was to borrow an external CD drive for my modern MacBook pro and replace the bunk files on the newer computer.
However, this initially did not seem to be effective as the cloud with the slash remained next to the files until they were played. After this, everything went back to normal.
Since it's unlikely that anybody else will have this very specific set of problems, this can probably just collect cyber-dust.
However, it would have saved me a headache to have seen this so this was the solution.
In short:
Get an external CD drive for a modern and updated version of iMusic and don't rely on older equipment when possible.
