I’ve also been trying to use dnsomatic to update cloudflare. After lots of testing this is what appears to be happening.
It doesn’t matter what host or domain you set in dnsomatic. Cloudflare will always update the value of the first DNS record that it finds on the first domain on the account.
Looking at the logs on dnsomatic it is sending the right information (may not be in the right format) to cloudflare. Looking at the audit logs for cloudflare show that a completely different thing is happening.
As an example I have the com, net, org for a domain. I’m trying to update an address on the .net domain. dnsomatic shows it sent the information for the host and domain correctly. However the audit logs on cloudflare show that it tries to update the mx record (first host found) on the .com domain (first domain found).