I would expect the code E Form 1099-R to be a 2021 Form 1099-R since it needs to reflect the distribution from the 401(k) that was originally intended to be a permissible rollover to the Roth IRA. A code JP Form 1099-R will be a 2022 Form 1099-R that you'll receive near the end of January 2023, reportable on your 2021 tax return if there is any taxable gain. To be able to file your 2021 tax return without amending later to add the code JP Form 1099-R you can enter the code JP 2022 Form 1099-R into 2021 TurboTax as if you have already received this form.
Section 301.9100–2 applies only if you already filed your 2021 tax return by April 18, 2022. If you requested a filing extension by April 18, 2022 you'll just file your 2021 tax return as you normally would, factoring in the code JP 2022 Form 1099-R. Section 301.9100–2 has to do with treating the corrective distribution as if you had requested a filing extension as long as you filed your 2021 tax return by April 18, 2022. If you timely requested a filing extension, there is no need to invoke section 301.9100–2.
