When I try to open the game I get a message saying I need bookshelf 13.0.6 but the latest version of bookshelf I can find is 12.0.23. Anyone now where to get 13.0.6 or is this a bug?

Hello,

13.x.x versions of Bookshelf are for MC 1.18.2 while 12.x.x versions are for MC 1.18.1. CurseForge is a bit annoying and does not show files sorted by version by default so the 13.x.x files are a bit lower in the file list. You can find all 13.x.x files here.