The data I see from iKnow is a sloppy clusterfuck, I suspect from botched syncs and lazy bookkeeping on my part, and the fluctuating quality of Apple's "services" over the years. My Mac settings probably go back to the 1990s and Apple periodically did a bad job. Pain points I remember: Google contacts being separated and then with a new phone not syncing correctly, Mac address book burping on contact avatar images, importing lists of contacts from short-lived 3rd party apps, shared Photos fucking shit up, the iPhotos upgrade fiascos, transient contact info for my kids, moving onto/off of Gmail, etc.
If the FBI got ahold of my (and others'?) iKnow data, a lot of people might end up in a sloppy jail with a sloppy judge sloppily applying a sloppy law...