One thing I didn't get was actually having to go to other countries to find other cultures. Like there's this one bit where Juniper is wistfully thinking of all the cultures/races that got decimated and might be extinct. OK...except the United States is probably the most ethnically diverse nation on the planet. See, I think Stirling had a real opportunity that he ignored or deliberately passed over: rather than just mixed groups basing themselves on Osprey book/Wicca/Asatru/Tolkien/utter lunatic, he should have had different ethnic groups banding together. Like...Korean refugees from LA creating a kingdom that they call New Baedal, or stuff like that. Because it's human nature in time of crisis to band together with other people like you - and I think the Change would qualify as a crisis
Which isn't to say that there shouldn't be mixed groups too. Obviously there should, given how well America assimilates cultural minorities - and as a product of the modern world, I think inclusivity is good. But there should also be groups who choose to identify themselves with one cultural and ethnic background...or, since they've been living in America, a highly distorted version of that cultural and ethnic background. Actually, a recreation of Edo-period Japan would have made more sense with Japanese-American survivors than actual Japanese...
There were almost never (in Oregon, specifically) enough people from one coherent background to assert that background into the mix that formed the proto-groups that went onto form the post-Change Oregon states. The folks who made it to, say, Larsdalen, were just too randomized to have an impact on the new culture (i.e. they became Bearkillers, just like Mike and Eric....not "Ninja/Pirate/Knight Bearkillers").
The two exceptions to this are the McKenzies (the core group essentially having Wicca as their defining factor, and not much else except Juniper's fake Oirish culture) and the PPA (which, beneath Norman's imposed aesthetic, is a mélange of SCA culture and Organized Crime culture).
You don't see any Samurai-themed Bearkillers because there were not a whole lot of Samurai/Asian-culture loving people joining up with the Outfit, which already had a fairly solid self-image as Polish-Mongol-Marines.
Ditto with CORA, which formed basically out of rural Oregonians (and whoever they let join them).
The non-core members of these proto-cultures (i.e. the folks who "joined" after the core fused into a coherent organization) were largely refugees from the urban areas and the inhabitants of the region the core group moved into (the Bearkillers moved into the Lardsalen region and took it over, imposing their corporate culture on everyone else, etc). Sure, if there had been a coherent group of a few dozen Koreans or a Kendo tournament in the location they moved into...that would likely have flavored things a bit.
OTOH, we see exactly what you are talking about in the form of the PPA* and the Buddhist State out in Wyoming (where a Buddhist conference was taking place when the Change hit, and the large number of Buddhists fused with the surrounding culture).
*-it's mentioned that in the Eastern end of the PPA territory, all the Baronies are quite different from the "classic" PPA model (due to the pre-Change local culture being much different from that of Portland, and Norman having to "recognize" local strongmen, rather than replace them with his Gangland buddies) . Due to ranching being big, instead of row crop agriculture, the knights and men-at-arms are mounted archers (and the nobility is a lot closer to the commoners, socially).
