Koko-Analytics with nginx cache

Hello,
I have setup nginx to cache page requests as described here:

https://restorebin.com/fastcgi-nginx-cache/#create-fastcgicache-configuration-under-/snippets/

For looged in users the caching is disabled in this tutorial by an if request as:

# Don't use the cache for cookied logged in users or recent commenters
if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+|wp-postpass|wordpress_no_cache|wordpress_logged_in|woocommerce_cart_hash|woocommerce_items_in_cart") {
set $skip_cache 1;
}

If I open my site in a new private window and access a previously cached site (by another person, not me) – I also receive a “x-cache HIT” in the server response – so I assume that kokos-analythics can’t set a cookie or count the correct amount of users?
Does anybody have experience with this or can help me configuring the cache correctly?

Thanks

mathse