I got an answer in the nokia developer discussion board, so credits go to them. Just in case someone is passing by, here is the solution which solved my problem:
nokia.mh5.event.add(nokia.mh5.app.controller.current.page.header.search, "success", function(e) {
console.log("results: ", e.data);
});
In e.data
you will find information about longitude, langitude, the address entered and more.