That's what you get for trying to use French!
I tested this on my Sprint Touch with stock 6.0 rom. Even after setting the input language to French, I keep getting an underscore in place of the accent characters.
If you keep hitting a wall, you might want to consider a third-party keyboard like TouchPal. It's been my default keyboard for some time, and I know that there are multiple language dictionaries available.
I realize that is a paid solution for something that should be included with the phone, but there is a free trial and depending on how important it is to you, it may be worth it.
Or instead you could always just say "a slightly larger violin".