As @Hms2 said, Ethan is based on an earlier version of Jasonette, which means it works mostly the same as Jasonette except that some of the syntax are different (the current API is much more refined based on the learning experience from Ethan)
I'm thinking about updating Ethan to use the latest version of Jasonette soon, so I can easily update it whenever I want, but that's a story for another day.
That said, I think it really depends on what you are asking about. Ethan app is not just a static JSON, all the logic is in the backend, such as storing chats, channels, chatrooms, favorites, etc. all in the backend. i used ruby on rails to write the backend, which makes this easier.
So if you're asking if you need to know programming language to build the entire Ethan app, the answer is Yes, because you still need to know how to write to database, serve the content, etc.
But this also really depends, because in terms of UI, you can build every single feature on the Ethan app using Jasonette. Jasonette is a UI layer to represent what exists on the server side.
Which means, if your app is not a dynamic social network or anything that needs to have sophisticated database, you can easily serve them all from static JSON, in which case you don't need any programming skills since you can just use Jasonette.
A good analogy is : "Do you need to know programming to make a website?" Nowadays the answer is mostly no, because you can just easily set one up on wordpress or squarespace or whatever. But if your question is actually "Do you need to know programming to make a Facebook?" Then the answer is yes, because now you need to store, manipulate and present user info and all the content in your own custom way.
TLDR: If you're trying to make an app that doesn't need any dynamic content (adding friends, creating posts, etc.) but allows for mostly consumption of content, you don't need to learn programming. You can serve static JSON and use Jasonette to present it and let people view and interact with it. To add content you can just update the JSON and it will have new content. But if you need dynamic logic, you need to write backend program first.
Hope this makes sense.