Hi meck08,
It sounds like music you have previously imported from CDS aren't showing up in the Music app on your Mac, let's see if this helps.
First, you'll want to see if you can find one of the files on your new Mac using Finder and the advice in Narrow your search results on Mac. This will help you to see if the file is somewhere on your new Mac. Then once you find it, then these steps can help you to import the file into Music.
1. In the Music app on your Mac, choose File > Add To Library or File > Import. If you selected “Copy files to Music Media folder when adding to library” in Files preferences, you see File > Import.
2. Locate a file or folder, then click Open.If you add a folder, all the files it contains are added to your library.These steps are from Import music from a computer to Music on Mac.
If you can't find the file at all through Finder on your new Mac, then you might be able to use Home Sharing to import media from the old computer to the new one. This will guide you Import media using Home Sharing in Music on Mac.
We hope this helps and take care!