I'ts a problem with the php version. preg_replace_callback doesn't support inline undeclared callback
Solved, trying to touch the minimal code :
Go to fop2/admin/pagebs.fop2buttons.php and in line 468 replace with this:
$plugin_section_print = preg_replace_callback('/#{([^}]*)}/',afunctionforreplace_callback($matches,$datarray),$plugin_button_section);
Then at the end of the file put this:
function afunctionforreplace_callback($matches,$datarray)
{
return $datarray[$matches[1]];
}