[gizmo]

The first link I get when I google "accuracy of death certificates" is this one:

The accuracy of death certificates. Implications for health statistics. https://www.ncbi.nlm.nih.gov/pubmed/1871957

> Significant discrepancies between the two documents were observed in 50% of patients. In 25%, the immediate cause of death was incorrectly stated on the certificate, having been assigned to a different organ system in the majority of those cases. In 33%, there was disagreement on major disease other than the immediate cause of death.

Anecdotally, elderly people I've lost had completely wrong death certificates. When common sense, anecdotal evidence, and a cursory review of the scientific literature point in the same direction I'm going to assume that's the way it is.

Also, try to be kinder in the way you communicate.