Hmm so how does the workflow look like for you? Is the calibre web tied up to the DB of that calibre VNC? Do you manually add the books to calibre over the VNC? Then is calibre web allowed to make changes to the DB or does it have read only access? as far as I understand calibre is not recommended to have multiple sources of changes to the DB as it can end up corrupted or something? (At least it can't resolve conflicts I think)

As a solution it seems like it could work, but it feels like over complicated to get around the limitations of calibre.