$form_values = $form_state['values'];

$nid_cid = 6;
$title_cid = 7;
$date_cid = 8;

$node = node_load($form_values['submitted'][$nid_cid]);

$form_values['submitted_tree']['ref_title'] = $node->title;
$form_values['submitted'][$title_cid] = $node->title;

$date = date_make_date($node->field_date[0]['value']);
$date_str = date_format_date($date, 'medium');

$form_values['submitted_tree']['ref_date'] = $date_str;
$form_values['submitted'][$date_cid] = $date_str;