PrePub - Ascendance of a Bookworm

There are more problems and unknowns than just the alure of books here.

1. We don't know for sure that every temple had their foundation door in what was originally the book room, when it was constructed.
2. What used to be the book room, might have been refurbished to serve some other function, which would make it not appear like a book room, but still contain the door.
3. The door itself might have been moved.
4. We don't know if priests from one temple, can pass through the book room barrier of another temple. If not, Rozemyne will have to break through by force, which will mean delays for that itself and being more exhausted when taking the foundation, meaning even more delays and potentially running out of rejuvenation potions.
5. The layout of the Ahrensbach temple might be entirely different, causing even more potential delays.

Thankfully there are also positives.

1. Between Ferdinand going to the Ahrensbach temple for ceremonies and Justus... being Justus, Justus is very likely able to provide Ehrenfest with the layout of Ahrensbach's temple and castle.
2. Rozemyne still being at least partially dyed in Ferdinand's colour might come in handy. If Ferdinand got permission to enter the book room, their similar mana might allow Rozemyne to pass through. If a literal god can't tell the two apart, there's a good chance a mere barrier can't either...
3. Considering point 2, it might even be possible for Rozemyne to just walk into the mana replenishment hall already, without any need to take the foundation. After all Ferdinand has access to it, so someone dyed in his mana might be registered by the barrier as "him" and be able to enter.
4. Rozemyne is carrying Ferdinand's name-stone. If the barrier only requires someone to carry the mana of an admitted person (like the brooches for guests of Dormitories worked, when Aub Dunkelfelger brought Rozemyne and Ferdinand into their dorm for ditter), just having the stone might allow Rozemyne into the book room... or as per 3, maybe even the replenishment hall.
5. Rozemyne has Ahrensbach's bible key, which might allow the person who owns it to bypass the barrier. Rozemyne did fully dye it after the Gloria incident, so she's the current owner.
6. Ahrensbach's blue priests are highly disrespected by their nobility and Detlinde in particular. Ferdinand very likely treated them considerably better than they were ever treated by any Ahrensbach noble. As a result I would expect none of them to be too loyal to Detlinde and Georgine and thus either open to being forced or coerced into cooperating, or probably even outright willing and eager to help Ehrenfest and Dunkelfelger.