I don't know if those residual entries in the registry are going to bother anything. It could be a case of much ado over nothing.
If you want to make a project out of it you might try:
- Re-changing the User account back to the original misspelled name.
- Copying the user account to a new user with the new name
- Then deleting the old user account.
That might get rid of a lot of the old entries.
But I really wouldn't bother unless there is a problem that affects the use of the OS. Is there?