There are three of Belle’s journals stashed away around Sanctuaries of the Banished in The Devil’s Roar. While one of the journals is easily accessible, two of them require you to take down an Eternal Guard and acquire the Sanctuary of the Banished Keys they hold!
Cinder Islet
You can find Belle’s Journal of the Dark Widow on Cinder Islet just outside the Sanctuary of the Banished door. Reading it will complete the Dark Widow Decipherer Commendation.
Brimstone Rock
You can read Belle’s Journal of the Veil on Brimstone Rock. It is inside the Sanctuary of the Banished, so you must find an Eternal Guard and defeat it for a Sanctuary of the Banished Key before you can read it. Use the key on the Sanctuary door to read the journal and complete the Veil Viewer Commendation.
Flame's End
You can read Belle’s Journal of the Unending Flame on Flame’s End. It is inside the Sanctuary of the Banished, sitting on a rock. Similar to the journal at Brimstone Rock, you must find an Eternal Guard and defeat it for a Sanctuary of the Banished Key before you can read the journal. Use the key on the Sanctuary door to read the journal and complete the Finder of the Unending Flame Commendation.
