It sounds like you've set up your subdomains as redirects, which won't work properly. Instead, you need to set up CNAMEs for your domains.
For oci-weekly.ruepprich.com, you would need to create a CNAME called oci-weekly that points to paper.li. And for oci.ruepprich.com, the CNAME would be called oci and would also point to paper.li.
These CNAMEs should be set up within your domains' DNS settings.
Once you set up your CNAMEs and remove the redirects, you can save your domains in your papers' settings.