Checking Fig.1 and Fig.3 in the project book (English version, 2017) and trying to understand how it works, I believe that circuit in Fig.1 is not equivalent to the one in Fig.3.
Fig.3 seems to collect the purpose of a resistor ladder (resistors working in parallel of those switches that are pushed) while Fig.2 does not. It can be seen when assuming two switches are pushed.
Could anyone double check this as well?
I suspect that most people on this forum who have the knowledge level to answer the question don't own the book, and so wouldn't be able to answer the question without more information.