I think it's very much case-by-case. We know a lot of old data was simply not preserved. We see some cases, like Aguadilla, where they seem to just use the on-screen data. But I think that at the very least they will have on-screen data for most...
Nor do I. But you have not drawn a distinction between the two. Do you assume (wrongly) that anomalies must be things of interest? A thing in the LIZ is anomalous, i.e. we don't know what it is. A thing described verbally by a witness may be...
My working hypothesis will be that it is more birds and balloons and stars and distant planes... always subject to being proven wrong.
But it's been birds and balloons so far, and we know that birds and balloons exist. An extraordinary claim...