Well, there you go -- no one really knew what the question was, so we all had the wrong idea.
Please try to be more specific next time, so we know what question to try answering.
The
calibre date added to library field is not a recognized Dublin Core field, and in fact is not recognized by any piece of software other than calibre (and possibly the Android app "Calibre Companion" which as the name suggests was specifically designed to recognize "whatever calibre knows about".