Does the Drupal FAPI support more than one AJAX callback?
Yes, you can solve it with core Drupal AJAX framework. You are already using $commands, you just need one more custom command.  

Javascript code to provide new command:  

(function ($) {
  Drupal.ajax.prototype.commands.change_title = function(ajax, response, status) {
    // Update the &lt;head&gt;&lt;title&gt; element.
    document.title = response.data;

    // Update the page title.
    response.data = response.prefix + response.data;
    this.insert(ajax, response, status);
  }

})(jQuery);


PHP code to call this command:  

  $commands['#commands'][] = array(
    'command' =&gt; 'change_title',
    'method' =&gt; 'html',
    // Selector targets Drupal 7's default theme &lt;h1&gt; title (Bartik 7.12).
    'selector' =&gt; 'div#branding h1.page-title',
    'data' =&gt; check_plain($form_state['node']-&gt;title),
    'settings' =&gt; NULL,
    'prefix' =&gt; '&lt;em&gt;Edit '. node_type_get_name($form_state['node']). '&lt;/em&gt; ',
  );


Original idea is taken from here.