Cron for multisite does not work
When doing http cron (with .htaccess changes, see https://github.com/backdrop/backdrop-issues/issues/3903 ) or cli cron, on a multsite install, it uses the civicrm.settings.php from the root and not from the sites/[site]/ dir.
It looks like it does not expect a civicrm.settings.php in CMSroot if you have a multiinstall. But to my understanding that should be allowed (and even normal)
In my case I have [cmsroot]/civicrm.settings.php for the default site and also [cmsroot]/sites/[site]/civicrm.settings.php for the 2nd domain.
When I look at civicrm.config.php it can not work. When it finds a civicrm.settings.php in cmsroot it will not look further.