Routing comments.php to a custom url after the submit button is pressed

o.k. the relevant bit of code that does the routing appears to be in
wp-includes/comment-template.php:

/**
 * Retrieve the link to a given comment.
 *
 * @since 1.5.0
 * @uses $comment
 *
 * @param object|string|int $comment Comment to retrieve.
 * @param array $args Optional args.
 * @return string The permalink to the given comment.
 */
function get_comment_link( $comment = null, $args = array() ) {
	global $wp_rewrite, $in_comment_loop;

	$comment = get_comment($comment);

	// Backwards compat
	if ( !is_array($args) ) {
		$page = $args;
		$args = array();
		$args['page'] = $page;
	}

	$defaults = array( 'type' => 'all', 'page' => '', 'per_page' => '', 'max_depth' => '' );
	$args = wp_parse_args( $args, $defaults );

	if ( '' === $args['per_page'] && get_option('page_comments') )
		$args['per_page'] = get_option('comments_per_page');

	if ( empty($args['per_page']) ) {
		$args['per_page'] = 0;
		$args['page'] = 0;
	}

	if ( $args['per_page'] ) {
		if ( '' == $args['page'] )
			$args['page'] = ( !empty($in_comment_loop) ) ? get_query_var('cpage') : get_page_of_comment( $comment->comment_ID, $args );

		if ( $wp_rewrite->using_permalinks() )
			$link = user_trailingslashit( trailingslashit( get_permalink( $comment->comment_post_ID ) ) . 'comment-page-' . $args['page'], 'comment' );
		else
			$link = add_query_arg( 'cpage', $args['page'], get_permalink( $comment->comment_post_ID ) );
	} else {
		$link = get_permalink( $comment->comment_post_ID );
	}

	return apply_filters( 'get_comment_link', $link . '#comment-' . $comment->comment_ID, $comment, $args );
}

and I could possibly use for example something like:

<?php
 $cust_url_route = 'https://your-domain.com' . $_SERVER['REQUEST_URI'];
?>

in comments.php to fetch the initial URI of the post. Then have the function route to that url.

Now if I can just put all that somehow into functions.php then it should work. Would require me to figure out how to pass the $cust_url_route variable to the comment-template.php piece of code in functions.php though. Right.

Besides being not the proper the way to do this as it hacks core code, is this a safe way to do it?

In the form in comments.php:

<?php $cust_url_route  = 'https://domain.com' . $_SERVER['REQUEST_URI']; ?>

<input type="hidden" name="var" value="<?php echo $cust_url_route?>" />

In wp-comments-post.php change line 93:

$location = empty($_POST['redirect_to']) ? get_comment_link($comment_id) : $_POST['redirect_to'] . '#comment-' . $comment_id;

to:

$cust_url_route =  $_POST['var'];
$location = empty($_POST['redirect_to']) ? $cust_url_route  : $_POST['redirect_to'] . '#comment-' . $comment_id;

It works. It would solve the problem for now.