While not technically filler episodes (they were bonus chapters in the manga, so not really filler?), they don’t really serve much purpose.
If there were episodes to skip, these would be them. We get some, umm, intermission (?) arcs in “Ghost Story in the Park!?” and “Silent Christmas”. Minnie freaks me out, but dolls like that are disturbing regardless… We continue to learn about the characters at a nice pace, and see more of what exists in the realm of the paranormal.
“The Doll House” and “The After School Hexer” arcs were also decent.