YES of course, they are ghosts, the main trait of ghosts in all cultures is putting fear in people. For balancing sake though, in my opinion only, the stress + horror at the same time might be a bit too much. I would reckon one or the other would be enough, where instead of horror (or stress), you get a debuff or something.

Also do these ectomorph have a higher spawn rate during no torch runs? I've done 1 run with this mod on, and it happened to be a no torch one. More than half of my fights during my long expedition has been with the ectomorphs. Thankfully it was an apprentice level, as i've barely managed to survive all of that with almost my entire party having heart attacks, since these guys do a lot of stress damage attacks.

Otherwise visually speaking, this is the most polished mod i've ever seen out of my 350 hours playing this game (310 of them being played with various mods). If you told me this was an official DLC for the game, i wouldn't have thought otherwise. The fact that many of the indie games on the market have people like you that can put out quality content on par with the official game, is the reason why modding is one of the best things in PC gaming.