That’s a tough one. I’d suggest you ask the CPA to pay the $5,000 and wait till you get the refund either off your amended return, or as a credit against next year’s taxes. Then you can repay him or her!
But I doubt your CPA is going to do this — even though it was his or her error.
Inept CPA to say the least, filing the amendment through a paper filing. It could take forever. Did you ask why the amended return was MAILED instead of filing electronically. Did he at least mail it registered with return receipt requested?? Just so you have proof the amended return was filed??
If no, ask if he has errors and omissions insurance because you are considering suing him — on my advice! Obviously that would cost more than the $5,000 — but you can make a public filing against his/her license.
Respond to the CP14 noting that an amended return was filed — by mail. You respond, since you cant trust your CPA to do anything intelligent! Then see what happens.