Ahem. You can use a french name to sound posh. Like bakeries all over the world do it. Other than that, I can guarantee you 90% of germans won’t speak french and despise the french people for not speaking english. So no. Most germans won’t speak french unless you find a way to force them. Cordialement… moi. Je suis Allemand.
(Edit: You can show me an example of a question and a german reply and maybe I can tell you what went wrong…)