The music
I have been able to find the end credits classical music and it's composed by Georges Delerue. It is known as the "Grande Chorale".
However, I am still hopelessly trying to find the short but melancholic track that is repeated several times during the candlestick scene when Alphonse (Jean-Pierre Léaud) invites Julie (Jacqueline Bisset) to sit at a table. Truffaut is trying to get the right look on Julie's face in that scene.
Any help on that would be hugely appreciated!