Steps to simulate the problem:-
1) Invoke file-roller.
2) Create a new archive.
3) Choose Edit->'Add a folder' option.
4) Browse to a Filesystem directory where you do not 
have r/w permissions. e.g. /root
5) Click on 'Add' button.

Result:
The error message is:-
'Could not add the files to the archive'
'You don't have the right permissions to read files from folder "%s"'

Expected Behaviour: 
The folder name should be displayed instead of the format specifier '%s'.