Hey i played through once and i think i got the good ending? I mean i guessed correctly who not to open for.. Anyway, well done on this, i think it had the foundations for a good mystery game, and as you mentioned, with more refined dialogue and art, it will definitely feel more polished and interesting. The characters seemed good and it wasnt really obvious who the killer is. I was a bit lucky i guess :D The trick or treat section was a nice touch and i think with more dialogue refinement it will feel much better. It could have some more interactions to gauge who the killer is.
Overall great effort, i understand it is very difficult to coordinate with 4 people in a short time, but i hope the learning stays with you!