Not so controversial. The vast majority of code is written in plain ASCII (and english), and I hope it will go on. Using non ASCII character in your code is a double failure.
Take an example: "trouvé" instead of "found" as a variable name.
1- You're right. Most people won't be able to type "é", "à"... with their keyboard. Working on that code won't be easy.
2: What is the meaning of "trouvé" ? How people could figure out that variable name ? Average coder will search for english named functions or variable.