You've stumbled on to one of the current drawbacks of DoT, in that there really isn't a good consolidated list of verified DoT servers. The stubby.yml.example file is different from the web page listing at dnsprivacy.org.
I'm using a 'custom' list that I make in csv format (you can see it on the router at /rom/stubby-resolvers.csv). Why csv? I had already written a general csv parser for the dnscrypt v1 support that integrates with the gui..
For the beta, it was a quick list that I put together from dnsprivacy.org. I just finished adding a list update capability for the formal release and will be making another pass on updating that list. Right now, I'm going to host the update on my onedrive, but plan an opening an issue to see if I can get the stubby development team to pick it up
In the meantime, I'm also going to also depend on the user community to provide feedback on potential missing servers (just like you did.....thanks!)