Edit the logo link

No You don’t have to have a child theme because of this, but I actually recommend to use one in principle.

You keep a good overview of the changed settings and in case of an update they will be kept.
It was sometimes necessary to rethink some code if there were major changes in the parent theme.

These snippets would be placed in the parent theme at the bottom of functions.php just before:
require_once( 'functions-enfold.php');
on that place where the comment is :

/*
 *  register custom functions that are not related to the framework but necessary for the theme to run
 */

what you are inserting here is what the link should be opend:

add_filter('avf_logo_link','av_change_logo_link');
function av_change_logo_link($link){
    $link = "https://kriesi.at";
    return $link;
}

except you have different entries on your installation or in htaccess file. Then it will redirect to that url style.
even in wp-config can be different settings.
What about your : Dashboard – Settings – General : WordPress Address (Url) and Site Address (Url)

your search results on google link to the non-www version ( you can enter that on Googel Search Console )