FAPI Fivestar settings in custom form
I am not familiar with mforms, but I see a few potential issues:

1)  your form doesn't have a standard signature ($form, &amp;$form_state, ...).  I obviously can't see how you're calling it, but this is not a typical thing to do.

2)  when getting the path of the css, you should be using drupal_get_path
https://api.drupal.org/api/drupal/developer!topics!forms_api_reference.html/7#attached

3)  widget is not a property of #settings