Try to start Anki by opening Terminal.app and setting LC_CTYPE=en_US.UTF-8
If it won’t work, maybe create a new Anki profile, open the Debug Console, copy-paste the following code, press Ctrl+Enter, add a new card with the audio file from Safari and run Check Media.
mw.col.conf["normalize_note_text"] = False
If it won’t work, I’m out of ideas and don’t know why Anki reports pronunciation_fr_tête-à -tête.mp3 as missing and as unused at the same time.