"Here the contribution includes the conversion?"

Never; that's never true. A Contribution is not also a Conversion and vice versa.

Either of these might be the first deposit to a newly established Account. But each of these is different.

"with the first tax year for which a CONTRIBUTION was made to a Roth IRA"

I believe that here, you are referring to "how long have you had a Roth account?"

One reason a good strategy is to contribute even $100 to a Roth as soon as you are a working individual, is to open and establish that Roth account, which starts the 5-year rule for having a Roth. Another strategy is putting into a Roth by the tax due date of the tax return, which establishes the Roth was opened in the prior year (the tax year, not the filing year).

 A Contribution is because you have earned income which qualifies you for a contribution to a Roth. A Conversion is a different method that funds a Roth.

I like investopedia:

https://www.investopedia.com/ask/answers/05/waitingperiodroth.asp

"What is the amount subject to tax and 10% penalty?"

It still isn't clear why you don't help your taxpayer by explaining that 2020's unique covid disaster distributions rules will apply and means they can avoid the penalty. Why wouldn't you want to avoid penalty? Have you read the Form 8915-E instructions?

I hate working on math, when the math isn't even required.