At the moment, accented characters are treated separately from normal characters when using a mention. This would be a problem if there are many users who use accented characters in their names.

An example would be as follow. Let's assume this instance have many users with the first name Adam, with different last names. It would be very hard to mention a person whose name is Adam Lündy since the mention only shows 5 results according to alphabetical order, and it is not as easy to type with accented characters.

By treating accented characters same as normal characters, then you can easily mention Adam Lündy by typing @adam lu