I do believe that Sophia's "curtsey" reflected the times in Europe . . . Princesses and Princes (many impoverished) were a dime a dozen from places that no longer had monarchies. Or, as I prefer to think, it may be more a sense of who's who . . . Diva's have there own sense of self-importance and Sophia had her standards!
05/11/1957 of Sophia Loren who curtseys whilst shaking hands with Queen Elizabeth II at the Royal Film Performance of 'Les Girls' at the Odeon, Leicester Square, London. | Metro UK
A curtsey fit for a Queen.
I am utterly convinced that your stance on any "customs" of royalty (from hats and gloves to curtsies) is uniformly dismissive. If you are French then you do not have a royal family. This is not a problem. But I, as a member of the Commonwealth do and I have, and, should the opportunity present itself again, would again curtsey to members of the BRF. That is my heritage and custom. Performing a (men's) bow from the neck may work for you as a man but, as a woman I find it just doesn't cut it.