Shogun is absolutely fantastic. But it's not quite the same as a for-export production; it was an American-led production team adapting an American novel trying to be as authentically Japanese as possible. With great success. You're absolutely correct about the period language. It seems to have been a hit in Japan, indicating they got it right: https://www.tokyoweekender.com/entertainment/movies-tv/shogu...

>> The new Shogun has been well received by Western audiences, but it’s been a monster hit among Japanese viewers — possibly because they know the story. They know who Tokugawa Ieyasu is, they know about his rival Ishida Mitsunari and the Battle of Sekigahara the show is building up to. It doesn’t matter that these characters and events have different names in Shogun. It’s not exactly clear why the author did that, but in James Clavell’s novel, Adams is named John Blackthorne and Ieyasu is Yoshii Toranaga.

Various people have pointed out that Japan makes a ton of https://en.wikipedia.org/wiki/Jidaigeki shows in a similar style (and with a similar vocabulary, making Shogun comprehensible to JP viewers), but for domestic consumption, and they don't really get exported. I guess having the character of Blackthorne as an anchor is critical for Western viewers.

While we're on the subject, this audience might like https://www.imdb.com/title/tt0066473/ , which was a true Japanese-American co-production war movie. Bit of a specialist watch as it's nearly two and a half hours long. Some uncredited assistant direction was done by Kurosawa.