A Moveable Feast was originally published in 1964, although the original text – which must surely be the one Danielle read – was restored by Hemingway's grandson Seán in 2009 (and translated into French in 2011): this edition is considerably bigger than the first edition, which was published posthumously and wasn't even finished when Hemingway died. In fact it didn't have a title: the expression 'a moveable feast' doesn't appear in the book, but was a phrase that Hemingway had used to describe Paris to A. E. Hotchner. It was Hemingway's widow Mary who chose that title.
The book was written decades after Hemingway's stay in Paris between 1921 and 1926, and is really a series of mainly literary reminiscences, of the author remembering his relationship in Paris with such writers as Gertrude Stein, F. Scott Fitzgerald, Ezra Pound, Ford Madox Ford, etc. The English title refers to the way the joys of Paris can be carried around in the memory, although this nuance is inevitably lost in the French translation.
I'm not too sure how many of Hemingway's sudden band of supporters will actually read this book, but that's not exactly the point: Paris est une fête, I suspect, is being bought on the strength of its title as well as Danielle's favorable words about it: the book is being adopted as a healing symbol, and that can't be at all bad.
My post earlier this year on Hemingway's house in Key West, Florida:
Ernest Hemingway in Key West