And I have to honestly admit that I don't really know what that
libscitbx_boost_python does. Could you explain it to me.
I'm not a c++ developer and I haven't read the entire code yet.

It provides a medley of functions to be used in C++ code that need to interact with Python.
But it is not a Boost Python extension, in the sense that it does not feature the

BOOST_PYTHON_MODULE(name)
{
...
}

section.

Luc