They’re up to something important here, and something very good. This is a sad story, and a very common one. As is well known, American commercial cinema would take forever to even acknowledge it, let alone do it justice. Here, just as film narratives are getting ambitious and stretching themselves out, it gets the detailed and sympathetic attention that it deserves.
Modern film customs and expectations might make us wish for a less dramatically emphatic, a more dramatically consistent rendering of this situation. That might not be quite fair, but it’s still quite understandable. There are a few legal and plausibility stretchers here, but everyone’s heart is definitely in the right place. Also, the scrupulous interiors, combined with the actual Parisian exteriors (as always with really old footage, humbling, even awe-inspiring), really do cover up or eliminate these small uncertainties.