It’s not that we set the hostname to some funny phpMyAdmin-only values. What’s actually happening is that you simply cannot connect to our database servers outside of our hosting. Regardless of what hostname you use.
You are kind of right that these hostnames are “fictitious”. But then it’s not like there’re two types of hostnames for one being fake and one being real — there’re no “real” hostnames for what you’re thinking of.
Now if you are actually connecting from within the hosting then it’s weird to get the message of host doesn’t exist because it’s unlikely, but anyways, the login info you’re using is created by Softaculous and can sometimes cause issues.
But again, this is for connections inside our hosting only. It doesn’t apply if you are connecting from outside.