It might be a great idea to post it in a separate thread so everyone can access it, if you would be ok with it). Another thing which you can do is to show how the input would work and how to address the buttons in the most common languages used (c++,c#,java,gamemaker,python,whatever else :) ).
Viewing post in I would like to adapt the controller code for Game Maker
Shared the Arduino code in this thread: https://itch.io/jam/100-button-game-jam/topic/140791/code-code-for-the-arduino
I'm not sure what you're asking on the other part of your question. Could you elaborate?
If you're still looking for a general-purpose API for talking to the board, and you've ever talked to a web service before, you might like the web adapter I just published: Buttons Are Cool Gateway Server
The server exposes the button board as a web service (HTTP GET and WebSockets). Most languages have good libraries for making web requests or talking to WebSockets.
Cheers!