So essentially 

English Version: Cas confesses his all consuming love for Dean and dies never hearing that he is loved in the same way. He dies believing he could never have such a thing. 

Spanish Version:  Cas confesses his all consuming love for Dean (Te AMO) and what triggers the deal is the fact that Dean says “Y yo a ti” (and I you), so he dies BUT he dies knowing he was loved in return 

French Version: Cas confesses  his all consuming love for Dean in the most romantic way possible and says “becaused you cared about me, I cared about you” (SO HE KNEW HE WAS LOVED) and then finishes the whole damn steel chair of a monologue with a “Je t’aime Dean”. 

In conclusion the english language is generic as fuck and is the most tragic of all 3 versions.