I've updated the template and moved the files to be loaded locally. Of course I broke the site at first by making a dumb copy-paste mistake and bootstrap.min.js wasn't loaded. For some reason the main.pageCache wasn't there after buildbot generated the page. That's why I generated the site locally and committed it to SVN to update it immediately.
Also, the release pages for all 5.8 release were missing in general, so I've added them to SVN. There are still a lot of external resources, including Google-Analytics. Shouldn't we load them locally, too? Any external resource is a possible GDPR violation without consent by the user. Cheers, Ben