Should I e-file my 2019 amended return or keep waiting? I filed by mail just over 6 months ago and it still doesn't show up in the "Where's my amended return" system.

A few days ago I called and spoke with an IRS agent who told me they are still WAY behind on this sort of thing.  I have nearly $1000 refund coming which I indicated to carryover to my 2020 return.   If I claim that overpayment on my 2020 return and they haven't processed my 2019 amended return yet, how's that going to work?