Not sure what is "no true" from my comment as you were not specific, but at least to the suggestion of installing heat-pumps in Paris, this will be a much bigger investment than putting "some A/C". I don't think such an investment is more beneficial than (for example) transforming more of the side street parking to bike lanes (which seems to be what is happening).
My point is just that viewing A/C as a luxury leads to more energy use. Yes, I think Europe needs to have a large scale deployment of heat pumps — not only for the climate benefits but also to lower dependency on Russian oil and gas. A/C just comes along for the ride as a thing that makes lives better. New developments like the Olympic village should all have heat pumps.
I would aim for maybe 95-97% of expected weather to be covered.
What is too hot for you? For me an average a mean high temperature of 25 deg Celsius in August is reasonable (source: https://en.wikipedia.org/wiki/Climate_of_Paris).