Cannot mod my French edition Modern Warfare 3 save

i bought mw3 online pal version. it came in french edition and cannot change language. i want to mod the profile on Horizon but it doesnt recognize as a moddable game. when u add a game u cannot edit like that shown. pls help.

Also is there any way to add an english text file without corrupting the game.
BTW its a retail console.

Thank you