Login in a Moodle site as admin. If it's not installed already, install the Spanish language (ES). Create a quiz. When creating it, in the "Overall feedback" section, add a couple of feedbacks (e.g. one for 100%-50% and another one for 50%-0%). Add 3 questions to the quiz, with 1 point per question.  Now login in web as a student. Go to Preferences > Preferred language and select Spanish. Now login in the app with that student and answer the quiz. Make sure to answer only 1 or 2 questions so the grade has decimals. Once the attempt is finished, go to the quiz entry page and check that you can see the overall feedback for your grade.