Ansel W.

Yes, I'd mark those cases as unassessable. I'd report their count separately and exclude them from the denominator for attribution-error rates, so missing family-member information isn't counted as either correct attribution or incorrect reassignment.

I'd retain the ambiguity. The adjudicated reference could contain several defensible concepts, each preserving the source qualifiers, without requiring one preferred label. For synthesis, I'd record whether a classification change holds across those alternatives or depends on selecting one. If it depends on that choice, I'd leave its justification unresolved unless additional source evidence distinguishes the concepts; agreement with one admissible concept alone would not settle it.

Yes, as a proposed admission rule. I'd assess preservation against an independently adjudicated interpretation of the source observation, including its qualifiers. Requiring classification to stay unchanged would make any correction fail that test, so the synthesis should distinguish justified changes from mapping errors.

Yes, I'd compare observation periods first and record conflict status as indeterminate when missing timing prevents that comparison.

I'd extract family-member attribution errors among mappings with the correct ontology term as a separate outcome. That would make your distinction measurable in the synthesis, while leaving studies that don't report attribution separately marked as unreported, without treating their concept accuracy as evidence of correct attribution.