PLUPLOAD_ERR_UPLOAD_LIMIT should be using plurals

'PLUPLOAD_ERR_UPLOAD_LIMIT' => 'Upload element accepts only %d file(s) at a time. Extra files were stripped.',

it should not be so

'PLUPLOAD_ERR_UPLOAD_LIMIT' => array(
1 => 'Upload element accepts only %d file at a time. Extra files were stripped.',
2 => 'Upload element accepts only %d files at a time. Extra files were stripped.',
),