Since 2012 an interdisciplinary and culturally heterogeneous team composed of more than 30 people has been engaged in the complex process of conceiving, designing and validating an online placement test with formative orientation called SELF (Système d'Evaluation en Langues à visée Formative), developed and already deployed in six different languages -- Italian and English as pilots, followed by French, Mandarin, Japanese and Spanish. Its results are used to form groups and classes of similar ability, or to identify students' strengths and weaknesses in three macro skills (listening, reading, limited writing). In this report, we describe the steps the multilingual team is currently taking to transform SELF into a diagnostic test that will fulfill its original formative purpose and provide students and other stakeholders with more precise information about their performance. This can be done in two ways, by using the data automatically recorded by the online administration platform more thoroughly and by enriching user feedback with clear and informative graphics. This will enhance the validity of our test, and help close the gap between testing and learning.