Some nitpicks
For a film which focused heavily on clothing, it was annoying that the costumes of the two male leads were consistently wrong. No man, especially not a gentleman, would be seen outside hatless during that period, yet both Boy and the French chateau bloke never wore hats in any of their exterior scenes. They would have been as unlikely to do that as they would have been to go without trousers.
I also found the last scene confusing. We see Coco in her workshop, and judging by the clothes of the staff, it was presumably around 1912. Yet the scene then cuts to a procession of models in what looked like 1960s clothing, walking down into a fashion show where the audience were clearly wearing short 1960s skirts. Yet Coco looked exactly the same as she had in 1912!