It would've probably been much less ugly if the author reverse engineered one of the mobile apps instead of the web version. Those must use a much saner API that actually feels like an API.
I myself reverse engineered and patched Instagram for Android once because I got fed up with ads in my feed, but there's a high probability that all Facebook apps use the same "proxygen" HTTP client library. This library is notable because it is written in C++, thus requiring JNI bindings on Android, and that part can't be obfuscated — so, easy to find and fully stable across versions.
So I just added some calls into my own code (java source -> javac -> dx -> baksmali -> copied to "classes" in apktool project directory) in the bytecode of those JNI bindings and started logging requests to see how the ads are returned. I then built a response rewriter to remove the ads. If you have a spare Android device, you could even avoid messing with the app entirely by injecting your own code into the unmodified app using Xposed Framework. Xposed is very underrated as a reverse engineering tool.
I myself reverse engineered and patched Instagram for Android once because I got fed up with ads in my feed, but there's a high probability that all Facebook apps use the same "proxygen" HTTP client library. This library is notable because it is written in C++, thus requiring JNI bindings on Android, and that part can't be obfuscated — so, easy to find and fully stable across versions.
So I just added some calls into my own code (java source -> javac -> dx -> baksmali -> copied to "classes" in apktool project directory) in the bytecode of those JNI bindings and started logging requests to see how the ads are returned. I then built a response rewriter to remove the ads. If you have a spare Android device, you could even avoid messing with the app entirely by injecting your own code into the unmodified app using Xposed Framework. Xposed is very underrated as a reverse engineering tool.