Created new world on 1.19 with Create 0.10
(edit: problem persists in v0.10.1)
Expected: guidebook would only have introduction unlocked, and would unlock with advancements.
Result: everything is visible, even the spoilers!
Also, things look "weird". Are the "icons" broken? See attached.

Whoops, the unlock is probably because I haven't rerun datagen in a billion years.

The broken text is a Patchouli problem, and the chamfered intersections is for accessibility (so you can actually read the pattern's stroke order). I think the Patchouli fix is to resize the book on the landing page.

Can you show your advancements screen, also?

Edit: Created a new world on v0.10.1, problem persists.
Mods are Enigmatica 9 v.1.2.0 (https://www.curseforge.com/minecraft/modpacks/enigmatica9/files/4091410) plus Hex Casting v0.10.1.
There are no Hex Casting advancements unlocked yet:

However, the book is fully unlocked. For example, the Mind Flay entry:

i haven't heard or seen of this before so I'm guessing it got fixed ?