What about 2019? Once Schwab helps me calculate what the $6K contribution equates to, do I need to do anything about the appreciation?
No! Schwab has no business doing any calculations in regard to the 2019 excess contribution. The corrective distribution for the $6,000 excess contribution for 2019 is a regular distribution of exactly $6,000. In fact, the safest thing to do to avoid Schwab mistakenly doing any calculations in regard to the 2019 excess contribution is to simply request a regular $6,000 distribution with no mention that it is to correct an excess contribution. They don't need to know why you are making a regular distribution.
Of course for the returns of the 2020 and 2021 contributions, Schwab does need to know that these are to be returns of contributions before the dues dates of your 2020 and 2021 tax returns, respectively, and they will need to do the gain/loss calculation separately for each of these.
