maybe she had no requirement to file a return because her gross income was less than her standard deduction. it's hard to tell because the tax laws say in determining gross income you take into account capital gains but not losses. can't say if she's allowed a FTC carryover. There are special rules for computing it when you have foreign long-term capital gains. form 1116 instructions https://www.irs.gov/pub/irs-pdf/i1116.pdf .the IRS accepting the return means nothing only that they got it not that they approve it. because of the omission and misreporting of data the IRS might have 6 years to send a notice requesting the missing info or to audit the return. doesn't matter that she no longer resides in the US. as long as she does not renounce her US citizenship, the US taxes her on her worldwide income.
since she has foreign accounts she may need to file annual FBAR reports.
penalties for failure to file can start at $1,000 per violation and go up from there depending on the factors involved.
see this link
https://www.irs.gov/newsroom/understand-how-to-report-foreign-bank-and-financial-accounts
as far as you preparing her 2021 return using the EA method, you can do what you want. It's for the IRS to find that rules have been broken and assert any penalties that apply. do note that her return is filed under penalties of perjury
