Sounds like this CD wasn't engineered to "Red Book specifications".
If you PLAY the CD, do you get 14 or 18 tracks?
If you can HEAR the 4 additional tracks -- even if you cannot "see them in the finder" to rip or copy them, I'd suggest:
1. Get something like audio hijack that can capture the Mac's sound output.
2. Play the CD with Audio Hijack enabled and saving the sound to an AIFF file.
3. This should capture ALL 18 tracks.
4. You will need to edit the captured audio (Audacity is free and will work) to "separate" each of the four "missing" tracks into standalone files.
5. Then take those files and covert to mp3, or whatever you want to do with them.