What you found on Lord Abbett's site (whoever that is) is misleading. In the example cited, you'd have to make the assumption that Maria's Roth conversion was the first time she ever had a Roth IRA account. With that assumption, the scenario is true. Any explanation of the five-year-rules just adds to confusion if it doesn't clearly distinguish between the two different rules.
You might want to look at https://www.fidelity.com/learning-center/personal-finance/retirement/roth-ira-5-year-rule. Note they say (emphasis added). If you read the first long sentence and stop, it does sound like, yes, you have to worry about earnings after a conversion. But then read the next sentence (emphasis added).
Roth conversions and the 5-year rule
The Internal Revenue Service (IRS) requires a waiting period of 5 years before withdrawing balances converted from a traditional IRA to a Roth IRA, or you may pay a 10% early withdrawal penalty on the conversion amount in addition to the income taxes you pay in the tax year of your conversion. There are a variety of exemptions to this penalty, however, including death, disability, and turning age 59½.
