Relabel author names from Login to Display Name when displaying Co-Authors Pro as a taxonomy in Search & Filter Pro

functions.php

// Replace Co-Author labels in Search & Filter Pro (default name = login/default value=slug) with display_name 

function filter_function_name($input_object, $sfid) {

	if ($input_object['name'] == '_sft_author') {

		global $coauthors_plus;
			
		//udpate this field before rendering

			foreach($input_object['options'] as $key => $option) {

				if($option->value=="")
					{//the option with no value is always the "all items" or unselected state
						$option->label = "All Authors";
					}

				else {

				$user = $coauthors_plus->get_coauthor_by( 'user_nicename', $option->value );

	    			$input_object['options'][$key]->label = $user->display_name . ' ' . ' (' . $option->count . ')';

	    			}

	        	}

	}
		
	return $input_object;

}

add_filter('sf_input_object_pre', 'filter_function_name', 10, 2);