There is no max length setting for real names that I am aware of. If a user tries to enter a name that is longer than 200 characters it will produce an internal server error. Very long names get truncated in the UI, so they don’t break the layout.
It might be a good idea to have a name length setting.
Setting a name to longer than 200 characters should give the user a proper error message instead of the current “500 Internal Server Error” message.