With the sound: I think I get the difference between the disgusting sound (it sounds like puking) and the success sound (it sounds like blablablabla), I just didn't associate the blablablabla with success, it's more like boredom. And the guy seems to puke cheese cubes at the same time.
With the plate: the item seemed to just instantly disappear which I commonly associate in VR with you dropping the item. Having it snap onto the middle of the plate and stay for 3 seconds while he "eats" it (or whatever) would communicate that you placed it correctly.
Thanks, this is a great effort!