Hmm.... Good point.
But for now with what we have, if I were doing bulk operations I would just use an untagged (or otherwise generic tag), and push the contents to an array as they complete. I don't know if they would be ordered, but there's no particularly explicit guarantee of order when choosing files anyway. If order were a consideration, I would implement sorting through the array based on content.
The array size and file count can be compared to know when all files have been loaded into array, or throw an error of there was a mismatch somehow.