I actually wouldn’t worry too much if they miss the occasional thing. Part of building up a good atmosphere and tension is having a healthy dose of paranoia, and the best way to build paranoia is to avoid signalling threats too much so the player isn’t absolutely sure if something is wrong. Having a music sting, for example, when the player “sees” that the doll has gone just confirms that something is definitely wrong, and in a weird way can be reassuring. The player will definitely realise something is wrong when the dolls actually start closing in, and it will be all the more surprising if they weren’t observant enough and missed the warning signs earlier. You could even make it part of the challenge, punishing players who get too comfortable and switch to auto-pilot mode. I think this is a balance that playtesting will help with, but I’d suggest to start with you keep it subtle and avoid trying to draw too much attention to the creepy goings on.
Referencing Amnesia again, the music that played whenever an enemy was nearby did help raise the tension when you were in danger, but it also occasionally had the effect of removing any doubts I might have had about my situation, as it basically screamed “THERE’S A MONSTER HERE!” and sped up that transition from looking over my shoulder to figuring out how to get past it. Certainly, there were times when the music kicked in and I couldn’t immediately see the enemy which had a panic-inducing effect, but imagine if I had been happily going on my way and turned round to suddenly see one of them approaching from behind without warning. I’d be begging for eyes in the back of my head after that!
If you don’t want to reveal too much to the general public, I’d be happy to take a look at some footage in private and offer suggestions (assuming you’re comfortable with that idea) 