Thank you for the feedback! Indeed, we didn't have time to add music to the game. :'c
I am using one SFXAudioPlayer per enemy so it's weird. But I copy/pasted it between them to keep the settings, and we discovered last minute that every enemy with the same sprite triggered the animation at the same time, because when you copy, Godot by default don't count this as "Local to scene". :/ We fixed it for the sprites but it might be the same thing with the SFXAudioPlayer.
Thanks for the tips!