WordPress Snippet

add_filter( 'get_comment_author', 'my_comment_author_by_nickname' );

function my_comment_author_by_nickname( $author ) {

	$comment= get_comment( $comment_ID );

	if ( $comment->user_id ) {
		$author= get_the_author_meta( 'nickname', $comment->user_id );
	} 

	return $author;
}

• https://ja.forums.wordpress.org/topic/141564?replies=3#post-194412(b:@source)