I just had the same thought. I had found a way to make kefir using commerical kefir, cooked organic milk, and a probiotic supplement from a different forum. Everything was going well, but I intended to use it only until my grains arrived.
I bought them off someone who had extra and when they arrived in the mail they smelled strongly of alcohol. I “washed” them for 3 days by soaking them in fresh milk every 24 hours for 3 days but still, it had that smell.
I finally gave up and just started making kefir from them. They would result in exactly the type of kefir you described: either watery even after 48 hours or curdling to the point that there was whey (water) at the bottom and the entire top of the jar looked like cottage cheese.
I had not tried any of those mixtures until today when it looked somewhat normal. I cannot say for sure if it is ok or not, but I will say that I have had the worst reaction of the whole treatment thus far. Again, who knows if it is from that kefir, but I am extremely nauseous during the same day as taking it.
I am tossing it out (4 quarts :/ ) today and buying new grains from a kit.