brb408wpb, have you made any distributions or Roth conversions from your traditional IRAs? If not, nothing needs correcting. Although you probably should have previously included on line 2 of Form 8606 an adjustment for the after-tax money rolled over from the 401(k), you can do that on the next Form 8606 that you file as long as you have not made any distributions or conversions prior to 2019. Such an adjustment requires your tax return to include an explanation statement describing the adjustment. Your year-end balance in traditional IRAs is only relevant to determining the taxable amount of distributions and conversions.
If you have made distributions or Roth conversions prior to 2019 after establishing basis in nondeductible traditional IRA contributions and did not prepare Forms 8606 correctly, the corrections might be rather complex.
If your Forms 8606 did not include on line 2 the previous year's Form 8606 line 14 amount, that's another problem that will need to be corrected.
