The Mr. Warren referenced in the title doesn't actually appear in the comic; it's a whole plot reference to a Lovecraft story, The Statement of Randolph Carter.
Yeah, Rebecca and Eloise are literally following in the footsteps of Warren, as in what occurred in the story is mimicked here. I'd recommend reading it, it's a nice short story. Be real fun to see Eloise and her family experience other Lovecraft stories like this.