The filter isn't searching only by name, but on (title, artist, genre, filename):
if (($commfilter == '') || (($commfilter != '') && ((mb_stripos($retarr['title'],$commfilter) !== false) || (mb_stripos($retarr['artist'],$commfilter) !== false) || (mb_stripos($file,$commfilter) !== false) || (mb_stripos($retarr['genre'],$commfilter) !== false)))) {
...
I can add date there, but don't think that it's good idea, because have to be changed if You add modifications into file (it's ID3 tags, for example).