No I did not change filenames of the files. Yes I did add text to pages in the "File" subject namespace. And yes I did change the caption of thumbnails to better text. "this caused over 50 files to be slotted as unused files" - No that did not happen; my edit comment was Special:UnusedFiles for many of my edits. Adding links to or thumbnails of unused files removes them from being listed at Special:UnusedFiles.