Set anchor target for admin bar nodes

Perhaps you could use $wp_admin_bar->get_nodes(); to get all toolbar nodes, then loop them through and modify the right nodes as needed. Something along these lines,

add_action( 'admin_bar_menu', 'customize_my_wp_admin_bar', 80 );
function customize_my_wp_admin_bar( $wp_admin_bar ) {
  $all_toolbar_nodes = $wp_admin_bar->get_nodes();

  if ( ! $all_toolbar_nodes ) {
    return;
  }

  foreach ( $all_toolbar_nodes as $node ) {
    // Skip nodes you don't want to edit
    if ( ! $some_logic ) {
      continue;
    }
    //Change target
    $node->meta['target'] = '_blank';
    //Update Node.
    $wp_admin_bar->add_node($node);    
  }

}

I can’t remember what properties $node has, but I guess there’s some sort of parent property that you can use in the if statement to skip the wrong ones.