1) I don't really get the concept of relations in their family. So those two girls are step-daughters to MC and to his wife? I think in some of the dialogs the wife mentioned that. So those girls are adopted or something. They might be the Children of Zeta, born by some aspiring priestess. And then adopted. Am I right? I know there is a note in the library but it's kind of hard to get through.
So in that case they are not relatives by blood, and their relations aren't like those we all used to, but rather like those described in Robert Heinlein's 'Moon's a harsh mistress' or in the Expanse series (Holden's family, Drummer's warband).
Would be nice if the developer provided a clear definition to their relations. It's disturbing to think of an incest. Also the younger sister looks like 'mother', and the older one looks like 'father', it's confusing too. I doubt now that even 'sisters' are relatives by blood.
2) There seem to be some other misconception. What of their age? MC mentioned multiple times that he got married 30 years ago or so. That makes him at least 45 yo, and his wife too. They look too young. I understand there might be some rejuvenate techniques, but still. Also when we see that old master who will become lord of Decayed, the MC already has a beard, and he isn't married yet.
3) There are clearly a mistake with dates. In the 'Trainee' note we see the same date as in the 'The Long Walk'. It is clear that 'Trainee' should have at least Y437, like in the 'Reflections'.
These things are important since the game has such profound take in history. Any porn without history is boring.