Romaboy,
var obj = {"sentences":[{"trans":"Коко","orig":"koko","translit":"Koko","src_translit":""}],"src":"en","server_time":26}; //это вы получаите
var text = '{"sentences":[{"trans":"РљРѕРєРѕ","orig":"koko","translit":"Koko","src_translit":""}],"src":"en","server_time":26}'