I think this is what SugarPlumFairy said below, but I would use the accents only if I were planning on pronouncing it in a way that was the best approximation of how it would be said in French. So with Amelie
, that means saying it ah-meh-LEE, otherwise, leave off the accent. It's there to tell you how it sounds. For something more neutral, like Adèle (which is my name) that is going to be said the same without the accent... I'm not 100% on my opinion but I'd leave it off. My family is French, so it made sense, but I'd think it strange in an English speaking family in an English community.
Nothing jeopardizes the sanctity of the American hamburger.