Currently you either are forced to include custom detail or not. Making them basically no different from additional codex entries. Just a bit cleaner.

What I'm suggesting is make it so you can toggle auto adding a custom detail easily per codex entry, not per custom detail.

Additionally make it so you can actually include these custom details manually by either context button in scene beat or by writing the name of the detail after the name of the entry

example:

Entry named James and Custom detail named Appearance.

It will be added if you write James' Appearance | James Appearance | James's Appearance