How can I check the status of a mailed tax return?

I made Roth IRA contributions in 2020 when I had no earned income, but withdrew all my contributions and earnings in February before the filing due date (April 15, 2021) when I realized. I won't be receiving my 1099-R from Vanguard until next year in 2022, but I need to file this year since I owe the 10% penalty tax on my earnings.

 

The 10% early withdrawal penalty on my earnings is the only tax I owe. I plan on filing Form 5329 by itself with a money order enclosed. It has to be mailed since I'm filing the form on its own. Is there a way I can check the status of the form?

 

I won't be receiving a refund since I owe taxes, so I can't use the where's my refund tool. I plan on adding tracking to my mailed form so I know when the IRS receives it, but how can I know if it was accepted? I can also always check to see if my money order has been cashed by the IRS, but I heard sometimes they don't cash payments for a year. Will I be fine once I see that my tracked form has been sent to the IRS address? It's my first time filing anything so I just want to be extra sure of myself.