The reduction in angle of sweep is absolutely normal: less trim drag with decreased sweep angle thanks to better flow management (thinner airfoil at equal structural load, less chord for increased laminar section flows and better structural distribution). Old airbus had reduced sweep thanks to the less available trim level (centrally to rearward loaded). Those are inherited from old conceptual design requirement (and made them slower in cruise).

B/w nice doc. Thanks you for the time putting that together… and sharing!