Oxwall script is using a username while creating a custom URL, it doesn't create URLs based on the user's real name. That is not a bug, that is the way software works.
ok, it may be like that... but as per logic and practically there should be "real name" of user instead of the "username" .. i m not forcing dear as i m not any software developer so i dont know how to argue this in terms of software language..
Consider about submitting your suggestion at the oxwall.uservoice.com, but using username in the blog's URL is usually a good idea. Most modern social networks do the same.