Your legal name is Jonathon but friends know you as Johnny. Should you be reported to facebook HQ for not using your legal name? What if your nickname distorts

Your legal name is Jonathon but friends know you as Johnny. Should you be reported to facebook HQ for not using your legal name? What if your nickname distorts its origins further, such as "J", which easily turns into "Jay". Have we know left the realm of Real Names? What if you prefer to go by a middle name? Or an ethnic nickname which doesn't have an obvious relationship to the original (i.e. Alexei -> Alyosha). What about the common practice of adopting a "Western" name for people who native names translate poorly into English? Is a facebook employee qualified to judge whether you're using your real name?