Duelingbook Forum

I've noticed that YGOscope (https://www.ygoscope.com/) was able to fetch some data from duelingbook (at least the rare instances when it works)
So I looked around for Duelingbook's API as I wanted to make an app similar to YGOscope, but more reliable. I found the following page : https://api.duelingbook.com/
The issue is that there is only documentation for creating custom cards.
Is there some hidden API somewhere or something that could help me ?

Yes, they are probably keeping the source code private for various security reasons.