Do you trust that to withstand 40+ C temperatures?
Yes, except they probably won't need to.
1) Paris is normally about 25C daily peak in Summer, above 30C not particularly unusual. But over 40C? Barely ever.
2) Humans could make buildings that were substantially cooler indoors than the daytime temperature outside hundreds of years ago. We haven't magically lost that ability: quite the opposite, we can be even better at it these days. Many, many buildings haven't bothered because it has been more expedient for constructors to just stick up cheaper buildings (or to favour looks over practicality) and leave the purchasers to pay to heat/cool them.
3) There are other, more efficient ways to cool buildings than AC, e.g. heat pumps. These are easily sufficient to make any temperature in Paris readily bearable.