Real talk though, the only actual Terraria horror mod I know of is Echoes of the Cavern which is unfortunately not very interesting or fun to do a playthrough with. It just adds one creature with some eerie ambience and it's very predictable.
Also Spooky mod is just a halloween themed mod from what I know (even if it has a few scary elements), so I'd say no because that'd be like if The Nightmare Before Christmas was supposed to be a horror movie.