assets/js/locales/bootstrap-wysihtml5.es-ES.js

/**
* Italian  translation for bootstrap-wysihtml5 by Mirko Tebaldi
*/
(function($){
    $.fn.wysihtml5.locale["it-IT"] = {
        font_styles: {
              normal: "Normale",
              h1: "Títolo 1",
              h2: "Títolo 2"
        },
        emphasis: {
              bold: "Grassetto",
              italic: "Corsivo",
              underline: "Sottolineato"
        },
        lists: {
              unordered: "Elenco puntato",
              ordered: "Elenco numerato",
              outdent: "Riduci rientro",
              indent: "Aumenta rientro"
        },
        link: {
              insert: "Inserisci Link",
              cancel: "Rimuovi"
        },
        image: {
              insert: "Inserisci immagine",
              cancel: "Rimuovi"
        },
        html: {
            edit: "Modifica HTML"
        }
    };
    $.fn.wysihtml5.locale["it"] = $.fn.wysihtml5.locale["it-IT"];
    $.fn.wysihtml5.locale["IT"] = $.fn.wysihtml5.locale["it-IT"];
}(jQuery));

Update bootstrap-wysihtml5.it-IT.js