Its probably not "Elezen" thats the problem but only part of it - best guess on my part would be "lez" - thats the "forbidden word".
The games filter for such language can work in funny ways... I remember reading about an incident where someone wanted to change their name after getting married. Their firstname ended in "an" and the first letters of the new second name would have been "al". They couldnt change their name because of that...

Try it with an "s" instead of the "z"? Since Au'Ra is already missspelled... what does it matter here? ;P