I don’t know why it’s not working, but here are some problems with your code that may or may not be causing issues.
Instead of using 2 acf_form() calls you should have only one and construct the field groups to be included before you call acf_form()
$field_groups = array('group_5***d');
if (current_user_can('activate_plugins')) {
$field_groups[] = 'group_5***b';
}
// in your acf_form() call
....
'field_groups' => $field_groups;
....
Doing the above will also eliminate the need to call acf_form() with 'form' => false
There is no post_category argument for acf_form()
To set post values use the argument “new_post”
.....
'post_id' => 'new_post',
'new_post' => array(
// wp_insert_post() arguments here
// https://developer.wordpress.org/reference/functions/wp_insert_post/
),
With the above in place there will be no need to get the term and set it in your acf/pre_save_post filter. You should be able to set it to draft by supplying just the ID and status to wp_update_post()
Another issue you might be having is not supplying a post title. Even if you do not supply a post title field in the form you should be setting something here and include it in the new_post argument array. WP has been know to have issue when a post is saved without a title.
https://www.advancedcustomfields.com/resources/acf_form/
