Most weight savings come from the bending relief due to the distribution of the load over the wing span instead of concentrating it all at the wing root (which is the case for a conventional design).
There is research done at a big American aircraft manufacturer which determined a limit on how far you could comfortably position passengers outboard. (I believe it was 13m). This airplane respects that limit, the outboard sections are used for cargo and fuel.
Disclaimer: I work at the same research group at the Delft University
I use Python for most of my general programming needs, but in an engineering environment MATLAB (unfortunately) still has an edge. As a programming language it’s quite sh*tty, but it’s strength is in the high quality toolboxes. I work quite a lot with constraint non-linear optimisation and I still have to find a Python or Julia library as flexible and robust as the MATLAB toolbox. I think Octave is a good FOSS compatibly solution, but the main strength of MATLAB (the set of toolboxes) is unfortunately missing.