@Pitch64 - I take your point, but as a front end developer myself, you just can't dictate to your users that they can't use any romsets with accented characters in. There a lot of problems with this. Firstly, you may have a set of 2000 where only 3 have an accented filename. You can't ask a user to go through all 2000 and weed out the accented ones. Also, users may lose games without their knowing. I'm also aware that recalbox is french, therefore it would surprise me if they would try to force the anglicisation of all game names (what about french games with a french title?).
The solution is often in things such as database encoding setup etc and shouldn't be too hard a fix. Essentially, I'm easy, but good design would dictate an accommodation of accented game names.