If you just want indication in the list that a book has Comments then you could add an icon to a column (e.g. Title) viz:
If you want more than that you could do something like this.
Create a Comments like custom Column - e.g blurb/Blurb
Move Comments to Blurb
Clear Comments (I prefer to do this separately after eye-balling the previous step)
The problem is: Blurb is marked up HTML text, but the book list columns are 'plain' text so the result can be very messy - which is why Comments cannot be shown in the book list.
To overcome that I cloak the Blurb column with an
icon with no text. My primary objective was to edit the Blurb from the book list rather than the Metadata Edit panels.
BR