The art and concept are both really interesting! A little town with a dark secret.
I think these kind of loosely scripted event-based adventures can be tricky to run because they often rely on PCs taking a specific action. In this case, I'm not sure what motivation the PCs would have to check out the vineyard house basement. From what I gather, the PCs are hired as caravan guards to protect the shipment on the road and not to raid the vineyard. After the first attack, I think a GM would need to add some clues/hooks that encourage the players to investigate the vineyard. It might be easier instead if the characters arrive in town in the immediate aftermath of the first attack, and a desperate victim/witness can provide some direction to the source for the players.
I also wonder if it would be a more interesting development to have a targeted revenge curse. What if specific NPCs were called out as members of the angry mob responsible, and only they were the targets of the vengeful mannequins? Some families could be broken instead of completely wiped out. Damaged characters being more compelling than dead characters and all that.