Remove the accent from your background's name. Instead of "professeur_layton_et_l_étrange_village-14.jpg", change it to something else, "professeur_layton_et_l_etrange_village-14.jpg" will work or simply "background.jpg" will also work.
You can either delete and re-add the background image with the corrected name, or you can manually rename it inside your beatmap's folder. If you do it the second way, you will also need to update the name in the .osu file for your beatmap so the names are matching.
After that, update the map through BSS and it should work.