If you were emailed that your return was accepted today, then your return must have been in the small test batch that the IRS takes in early. You cannot amend your return until it has been fully processed by the IRS. That will take about three weeks or longer--if you are getting earned income credit or additional child tax credit it will take even longer, and your refund will not come until late February/early March. The Form 1040X typically becomes available no sooner than mid-February--or later. Form 1040X has to be printed, signed and mailed; it takes about 4 months for the IRS to process it.
As for what the lender will have to say, we cannot guess. It seems odd that a lender would want your 2019 return in January of 2020. Usually they want to see returns from the two previous years.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
