Weird West: Definitive Edition

Found in Chapter 4 as the Werewolf. Proceed through the story until you bump into Essex talking to Cleric Franciscus in the Absolution Hall. After the conversation Sybil and her Journal should now appear in Franciscus's basement. To gain access to the basement simply move the curtains in his office and use the hidden lever. This will move the statue and give you access to the basement. After a brief conversation with Sybil you can use a "Lightning in a Bottle" to open the door behind her and access the Journal.

Doing so will make Sybil and the other Werewolves hostile. I suggest saving before doing this so you can revert to an earlier time if you don't wish to upset the Werewolf storyline. But personally they all need to die after what you find out in the journal!

Chapter 4:

To get to the journal, you must be in the area you spawned, Absolution Hall and go into Franciscus's office. There you open the curtain which will reveal a switch which moves a statue and reveals a trapdoor. In the main room underground there will be a door that needs to be powered by lightning. Use one of the lightning grenades to power both terminals and open the door where Sybil's journal will be on a pedestal.

Notes: Sybil will become hostile upon reading.

If Sybil is killed in the basement, Fransiscus will come down and after dialogue will become hostile, causing the community to also attack you on sight.

If Sybil chases you out of the trap door and is attacked (even in retaliation), the whole community will become hostile.

If you manage to escape the area and travel, Sybil and Franciscus will stop you mid travel and become hostile after some dialogue.

Seems so far that there's no way to get the truth to Frankie and prevent fighting all the wolves after reading that journal.

I did notice that upon the very start of the wolf story that Sybil wasn't present in the basement which is when I first found the door.