I'm from Europe and almost everything in the game before she begins to get corrupted is actually very realistic. I mean I don't know about your mom but my mom wouldn't play basketball with teenagers, wouldn't walk around the house with the bathrobe having guests or not, wouldn't take compliments from strangers well etc.. A lot of "wouldn't" just like Sophia and I even think the opposite. She is quite, let's say, opened up. But then again i'm from Balkans, different culture here, more conservative
I think that is the difference, the Balkans and Middle Europe with their various traditions. To answer some of your examples:
a)The bathrobe thing seems to be some rather American use, AFAIK. Here in Germany it is uncommon too to walk around all day only with a bathrobe. It happens, but is rather uncommon.
b) Moms and Dads playing sports with their kids and friends is nothing unusual here in Germany. In the newest generation this might be a bit more rare than earlier, due to smartphones, etc., but no one bats an eyelid if parents play sports or games with kids and friends.
c) Compliments from nice strangers might be met with a short smile, "packed away" and no further reaction, rude "compliments" from strangers will be met with a glare and maybe some words. That is the general reaction, it can vary depending on age, personality and region.
But these examples you gave are not why sometimes the immersion breaks for me. From my German perspective Sophia´s reaction is over the top concerning e.g. her son seeing her in a bikini, the changing rooms and sauna.
Bikini: I do not know how many million Germans saw their parents, friends or kids swimming, playing, sunbathing, etc. in Bikiniis, swimsuits and trunks, even topless or nude, without going blind or having a mental meltdown.
changing rooms: communal changing rooms for men/women are quite common in sports arenas and swiming pools. And no one bats an eyelid or goes towels everywhere.
Sauna: while women/men only sauna times exist, normally sauna in Germany is mixed and naked. Dot. Swimsuits are forbidden, you go with a towel and nothing else.
Just a few examples, problems with this mostly come only with people from the various "Farawayistans" where the Middle Ages are still in the Future.