Actually, it’s semantics. “Evidence” is not “proof.”
I am assuming that some documents are so vital and important that their location is tracked. (I will admit that I’ve never worked in a situation where such a process exists. I do, however, believe that this is a distinct possibility.)
So (hypothetically), if NARA has a record of the existence of a particular document, and then they find that they don’t HAVE the document, they can look at the tracking. If the tracking shows that the document was taken by a particular person, that would be “evidence” that said person has the document.
If the document is found in said person’s possession, that is “proof.”
I meant by “weasel words”: “probably,” “likely,” etc. I would not be surprised if they were tempted to use such tracking in some kind of argument to convince a court that Trump was guilty of something. But I think their immediate goal is to suck the air out of the room, thereby changing the subject from Biden disasters.