- %AUTHOR% is the user who uploaded the last file revision. CommonsHelper2 used the imageinfo API. FileImporter does have this information already.
- %TRANSFERUSER% is straight away the user who is performing the current import.
Please note that the whole reason this feature exists might become irrelevant. CommonsHelper2 was doing the file upload with the user account which performed the upload. Therefor template replacements like ;self:self|+author=%AUTHOR% existed to not loose the information about the original uploader. This is not relevant any more with FileImporter. Therefor the entire magic word feature might be irrelevant.