I don't truely understand the problem with the American flag, especially with this cemetery. I mean they fight for the country so they had represented it for a moment of their lives and in my opinion, bringing a flag is like showing the country is thanksful. I work in funeral and do memorial plaque, and when there is a dead soldier the family ( or friends ) ask for a flag. I do think it is understandable. It is not disrespectful. https://www.plaque-funeraire.fr/en/