I smiled at your "could not duplicate on the ground" remark. I once had an engine that ran back to ground idle when the thrust levers were closed in flight. I wrote it up in the Tech Log as described. The engineer's write-off was, as you said, "could not duplicate on the ground".
Glad you smiled,
Old Smokey! It's good for the soul!
I would not find that to be an acceptable signoff either. I hope the engineer in question was embarrassed, rather than indignant when you confronted him!
Best regards,
Westhawk