I think you have to change the report.php
and change the code for ods xls and txt. I think (not did it) you can add an extra row to all this options.
ods line 130
$myxls->write_string(0, 7, get_string("city"));
then line 150
$myxls->write_string($row, 7, $user->city);
maybe this can work, but i didn't try it