Ty for your help 
like this it’s work yes “/api/resultats?locale=en-EU” but not if I put the he rest of the URL after:
‘&filters[Slug][$eq]=${slug}&populate[0]=resultats&populate[1]=Illustration&populate[2]=resultats.Image`’
idk why or how do this … I really need to fetch elements with the good locale and filter them in the same time i don’t want to fetch them all and apply filter after it’s really annoying 