Is it common practice for book reviews editors to be excluded from chief editor(s) meetings?
This is going to vary from journal to journal. Still, it's unlikely they're intentionally excluding you for nefarious reasons. More probably they're simply doing it because of inertia (it was always so, why change it?) or because they think you might not be interested (sociaca88 is probably busy and we're not paying her so we should try not disturb her, etc).
If you want to join the meetings, you can just ask. Be sure to mention &quot;which books to focus on&quot;, which is a great reason for you to attend the meetings. They probably won't decline as well. Only caveat is there will probably be broad swathes of the meetings which are not relevant to you and might not be of interest to you.