xprofile_filter_comments( array $comments, int $post_id )

function xprofile_filter_comments( $comments, $post_id = 0 ) {

	// Locate comment authors with WP accounts.
	foreach( (array) $comments as $comment ) {
		if ( $comment->user_id ) {
			$user_ids[] = $comment->user_id;
		}
	}

	// If none are found, just return the comments array.
	if ( empty( $user_ids ) ) {
		return $comments;
	}

	// Pull up the xprofile fullname of each commenter.
	if ( $fullnames = bp_core_get_user_displaynames( $user_ids ) ) {
		foreach( (array) $fullnames as $user_id => $user_fullname ) {
			$users[ $user_id ] = trim( stripslashes( $user_fullname ) );
		}
	}

	// Loop through and match xprofile fullname with commenters.
	foreach( (array) $comments as $i => $comment ) {
		if ( ! empty( $comment->user_id ) ) {
			if ( ! empty( $users[ $comment->user_id ] ) ) {
				$comments[ $i ]->comment_author = $users[ $comment->user_id ];
			}
		}
	}

	return $comments;
}