Actually, I think you may be right. There was the word “itchy” by her supposed corpse. I think it was supposed to say “twitch” or something, and was a nod to her possibly still being alive.
And I bet she’ll lead the duke and others to where they are. Cause I’m betting it was formerly her house with her son.
That’s an interesting idea. I had an idea that Luca might know where it is since we haven’t had much info given to us about his time in the slums, and Judith’s info doesn't seem as detailed as she initially believes. Perhaps he got some info on Franz’s strongholds either during that section she mentions or after the end of the book
My head cannon is Franz is such a failure he failed to kill Isabella.