Unless you are talking about two different companies that your wife participates in, it's clear from the totality of your posts that the company is an S-corp and your statement in the original question that your wife is a sole proprietors is incorrect.
A shareholder in a S-corp is not permitted to claim a self-employed retirement deduction on their individual tax return (or take any other deduction for contributions to the solo 401(k), so it seems whatever the TurboTax expert said to do to report this contribution on your individual tax return is incorrect. Any elective deferrals by the shareholder must be made from pay, reported with code D in box 12 of the shareholder's W-2 and excluded from the amount that would otherwise be present in box 1 of the W-2. These contributions are deductible on the S-corp's tax return, not on the individual's tax return.
Entering the amount contributed as income from self-employment is wrong. Shareholders in an S-corp are not self employed. You need to undo that. As AliciaP1 said, it seems that you need to amend your Form 1120-S, issue corrected Schedules K-1, and, if the contributions included elective deferrals or Roth contributions, correct the Forms W-2.
