Its not that Europeans havent read Mearsheimer. its that for the best part of three hundred years the whole of Europe has been trying that same realist script until there was nothing left but total ruin across the entire continent. Europeans who created the EU knew about balance of power geopolitics so well, they created this slow bureaucratic mess specifically to stop Germany and France sliding back into the same old lethal habit. While clumsy positioning between the US and China is a headache in the present moment for Europe, compared to a tedious Union Europeans prefer reawakenings of 1914 in their backyard. Well at least so far.
I would bet any amount that if you go to a random European city and stop 100 random people on the street you'd be lucky if one person has even heard of Mearsheimer. I think you're also overthinking how the EU got created. I don't think pre-EU Europe was on the brink of violence either. It was more IMO simplistic (but possibly correct, who knows) thinking that it's stronger (economically) as a block. A lot of present day Europe issues that might lead to bigger problems are potentially worse because of the EU.