The reason the nameserver validation fails is because the nameservers of qzz.io are severely malfunctioning. I explained that in more detail two weeks ago to someone else, and it appears that nothing has been done to fix the issues on their end.
The nameserver validation for addon domains and parked domains is the same, but due to how broken the nameservers are, you’ll see the DNS verification fail intermittently.
As for the too many dots error, that’s an issue with the hosting platform that should be addressed.