buddyforms_update_form_title

buddyforms_update_form_title.php

<?php
add_filter( 'buddyforms_update_form_title', 'buddyforms_update_form_title_user_id',9999, 3 );
function buddyforms_update_form_title_user_id( $post_title, $form_slug, $post_id ) {
	$post_title = str_replace('[post_id]', $post_id, $post_title);

// in here 
	$post = get_post($post_id);
	$author_id = $post->post_author;
	$post_title = str_replace('[author_id]', $author_id, $post_title);

	return $post_title;
}