What is the proper coffee to water ratio for a cold brew? I did mine with 100grams of coffee (an Ethiopian light roast) and a liter of water, and brewed for about 12 hours. It tasted good to me, but my friends said it's too acidic for them, hence I find it acidic in a way that the sweetness is present and with clean finish.
It depends where you look. When you create the concentrate some people say 1:2, coffee and water, some say 1:1. It really depends on how you like it.
Not sure about your target, but you can try various combinations, until you and your friends find the "right" balance.
The coffee-to-water ratio does not influence much acidity, in my experience. Cold-brew coffee is usually more acidic.
You could try another roast. Darker roasts should bring more strength to the taste, and perhaps counter-balance the acidic aspect enough.
As mentioned in answer and comments, it depends on your actual target, and related questions here can give you ideas.