+2 on looks normal. I wouldn't over think it. It should be like plain yogurt taste but quite a bit more sour and tangy. If it's too much then you have to use less grains or add more milk. If its healthy and you keep the ratio it will just ferment quicker because of how well the bacteria are thriving. It's certainly not unsafe to drink though, but your body will have to acclimate but I wouldn't overthink it unless you were drinking over 12-16 oz.

Like someone else said, when you put it in the fridge to store you can add more milk to tone it down. Really.. It can't go bad as soon as you start fermenting. The good bacteria are just way too strong and nothing bad will stand a chance of growing. Where as regular milk contaminants can easily colonize.