First, let me explain that hybrid apps built with AppBuilder have a /www folder. All the files and folders that you see in the AppBuilder client are then packaged into it. If you build an app package, rename it to a .zip and extract it, you can find the /www folder. It's located in a different place depending on the platform. For Android apps it's in /assets/www. For iOS apps it's in Payload/CordovaXXX.app/www.
That being said, the proposed solution in SO is suggesting you should modify the Cordova source files themselves. Telerik AppBuilder works with predefined stable and tested versions of Cordova for each platform and doesn't let you change the underlying source code. Any changes on the Cordova framework code can potentially break the whole framework and that is why we don't let you override the source code.
Moreover, the suggested solution is quite old and sounds like something that breaks the application sandbox model. Several versions of iOS and Android have been released since then and I can't guarantee it will work even if you try to do this with the bare bones Cordova CLI.
The common scenario with games and assets driven apps is that you don't have to update your source code. It's shouldn't be that big. You should have all the source code in the app and download all the necessary assets - images, data in the form of json, audio, video etc when the user wants to activate new stuff. You can easily download assets using the Cordova File plugin and then cache them in your app. Most big apps on the App Store are small and download huge amounts of assets on first startup.
You can also check out the AppManager LiveSync
feature that the Telerik Platform provides. It is available only for the Enterprise subscription level. It won't let you download chunks on demand, but it will let you update your front end code without the need to go through the store publishing process.
I hope this information helps. If you have any questions I will be glad to answer them.