That quote is plain wrong for sure, port cities would of had plenty of diversity in the form of traders, rural Bohemia would of been a different story though I doubt many would have any interaction beyond stories.
So I wouldn’t say the lack of poc is historically inaccurate given the size of the towns in game but I think the devs should have added travellers or a poc trader.
As to sexism there’s a dlc which allows control of a female protagonist, it doesn’t suffer the damsel in distress that some other stories do and was fairly enjoyable, bit of a bandade.