My experience:
Migraciones is a PITA. Not only within 6 months but if you enter and re-enter the country between the FBI background check and them accepting the document, they won't take the document and they might even tell you why or just silently sit on it.
Citizenship, the judge, as far as I can tell here in Entre Rios, seems to be pretty laid back. They're more concerned on the substance. (if you spend most of your time in Argentina and your FBI report is old, the individual judge might not care, but again, up to the judge).
Apostilles are super delayed right now in the US due to pandemic restrictions in DC. Fast passport services are similarly impacted. You'll need to wait a bit there.