If the contributions were after-tax contributions to the traditional 401(k) (normally tracked in a separate sub-account, but not a designated Roth account) your wife must obtain a corrected Form W-2 from her employer.
Code AA is only for Roth 401(k) contributions. After-tax traditional 401(k) contributions are not reportableon a W-2, although the employer can note them in box 14 for informational purposes.
