Lost Data Audit Trail

System

TeamSite 5.5.2 on W2K.

I have a user that claims changes they made to a templated file before going on vacation in early August were lost. I can't find any record of those changes in the file history and I can't find anything about the files in iwevents.log during the period in question. There seem to be date gaps in the iwevent.log backup files (I don't administer the server, so I have asked for an explanation), and anyway, lack of evidence does not prove lack of activity (if the system lost her data, would it have logged it?). So I can't convince the user they never made the changes. I am wondering if there is any other place to look for a record of her activity. Any (combination) of the following seem entirely possible to me:

TeamSite actually lost the changes.
The user made the changes to the wrong DCR.
The user did not save the changes.
The user generated the wrong file.
The user did not submit their changes.
The changes were reverted by get latest or equivalent.
Somehow locking was defeated and another user edited the file at the same time.
The file has since been generated from a different DCR.

There could be a number of additional causes (there are so many ways the user can error in this system!) It seems to literally impossible to track the data and activity through the system using the events logs and file history - are there any other options?

Thanks,

-John