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.
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.