We use a custom child theme of https://wordpress.org/themes/hueman/ for
siebenlinden.org , but did not update the main theme since a year or so.
We could need some help by some professional to make our child theme
compatible with the newest version. It’s not trivial, but on the other
hand there is nothing too special or fancy going on. Anybody with
(slightly) advanced HTML/CSS knowledge and understanding of Wordpress
should be able to get the job done.
Interested? Just answer or send me a private message.