Inline fields on node edit form
Display processors are not used when rendering the node form. It's a completely different process. I'm not aware of any contrib modules that will help you accomplish this. However you can write your own.

You need to start by creating a very simple custom module with just a .info, a .module and a .css file. You can find lots of tutorials online. 

Then you want to write that CSS to make your particular form fields inline and attach the css to the form using hook_form_alter. If you named your module "hook" the code would look like this (This code goes in your hook.module file):

// Replace hook with name of module and yourcontenttype
// with machine name of your content type
hook_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  if ($form_id == 'yourcontenttype_node_form') {
    $form['#attached']['css'][] = drupal_get_path('module', 'hook') . '/hook.css';
  }
}


After that enable the module, clear all caches and it should be including the new CSS in the admin form.