I wonder if one alternative is to treat earlier entries as collectables that you have to track down, similar to the Bozjan Field Record.

There was an interview that Ishikawa did around the time of Stormblood where she notes that they didn't really have time to go into the motivation of earlier villains like the Knights of Heavens' Ward and what they had been through, in part because there were so many of them. They show up, fight, and then they're gone. If they slowly release collectable lore snippets, it could give players the opportunity to piece together their history without relying on an external source, like the 'Tales from...' series of short stories. That way you can have the spoiler-free base version that allows newer players to roughly keep track of characters, with the full spoiler details appropriately gated behind a codex drop or even from reading through books in the world. You'd be 'lore hunting' in a way.

They could add a 'places' section, but if it becomes more detailed you might end up giving away the 'nature' of certain entities depending on how they're categorized. What it really needs is a search bar.

Also, for players asking for a 'bio' section on the Adventurer's Plate, it would be neat if you had your own little entry in the Codex with space for a quote and a short history.