You can edit the plugins primary facebook.php file. If for some reason I have to release another bug fix before I can release 0.9.0 you will lose the changes.
Starting in 0.9.0 I plan to start using WordPress’s built in humain_time_diff() function to create that date/time string. I would expect that when I make that change it will handle the localization for us.
If you locate the following in facebook-feed-grabber/facebook.php starting on line 77. Edit the values of today, this_year and other_year using the formatting option provided by PHP’s date() function.
// Date formats for event times.
public $date_formats = array(
// Event date formats
'event' => array(
'today' => '\T\o\d\a\y \a\t g:ia',
'this_year' => 'l, F jS \a\t g:ia',
'other_year' => 'l, F jS, Y \a\t g:ia',
),
// Date formats for when something was posted
'feed' => array(
'today' => '\T\o\d\a\y \a\t g:ia',
'this_year' => 'M jS g:ia',
'other_year' => 'M jS, Y g:ia',
),
);