> You’re right that a single hallucinated line is not evidence of reckless disregard

It absolutely is.

> - because that could have happened on a final follow-up pass after you had performed due diligence.

A "final follow-up pass" that lets the LLM make whatever changes it deems appropriate completely negates all the due diligence you did before, unless you very carefully review the diffs. And a new or substantially changed citation should stand out in that diff so much that there's no possible excuse to missing it.

> It’s happened to me.

Then you were guilty of reckless disregard.

> I know how challenging it can be to keep bad patterns out of LLM generated output

If your research paper contains any LLM generated output you did not manually vet, you are a hack and should not get published.