At first, congratulations for your fantastic search engine : it's far the best !!
Thanks! Could you consider saying this in your blog? Getting attention is the hardest thing about writing plugins and having people write about the plugin helps a lot.
You don't get any results, because for Relevanssi, e and é are two different letters and won't match. There's no easy fix, but one way to solve this would be to index words both with accents and without them. That way fatigué would be in the index both as fatigué and fatigue and would be found either way.
I suppose it would make sense in most cases. In Finnish it doesn't, as nobody will search for letters ä, ö and å using a, o and a, but I suppose with most accented letters it would be useful. I'll add this to my to-do list.