Wiki lists lore books as having <name> while this is true if you browse through the file structure, to actually spawn a codex requires <name>-codex. This is unfortunate as the wiki searches for files named with the previously mentioned itemName come up inaccurate as there are no files <name>-codex. After adding in a few and noticing data missing I have rolled back my changes (working on it), and made this post to see if an admin can see about working out a fix for this issue.
The id of the item in the item files doesn't have the -codex after it, that's what the wiki uses to match data. If you expand the data section under the codex pages it will show what the spawn command is for each codex though (id-codex), you can copy paste spawn commands for most things from there. I could easily add the '-codex' to the 'itemname' section at the bottom of pages for all codexes if you think that would be easier to read (by adjusting the template, not editing each page).
