Yes, there definitely is a language barrier. Most Japanese can‘t speak English very well. The average bloke on the street here can read basic sentences and talk a bit of broken English in a pinch. Occasionally you‘ll come across someone who speaks fluently. They probably lived overseas for their job or something. The public school system & media have been saying for years that kids are learning new ways to study English and will be fluent in no time at all. Well, those kids are all adults now and not much has changed.
As for older guys from the 1970s Quad era, English is pretty much a no go, especially with any technical discussions on gear and recordings. Walking around Tokyo, I haven’t come across any honey holes of vintage Quad equipment. There probably were some until the internet & downloading came along. During the past 20 years, though, even regular 2-ch stereo equipment shops have been disappearing. And no doubt this COVID nonsense is putting the final nails in the coffin of any small, independent shops still lingering around. I do see some discussions of Quad on the web in Japanese. So, there is a small, underground Quad scene.
In terms of new 5.1 and Atmos surround amps and universal players, I can find new equipment in the big box shops in Tokyo. So, obviously there are surround enthusiasts here. Movie theaters here offer a variety of visual & audio formats: IMAX, 4DX, MX4D, Dolby Atmos, etc… I don’t go to theaters as a much as I used to, so I’m a bit out of the loop on that scene. But I hear a lot about this stuff from folks around me. Twentysomethings are really into the immersive Audio/Visual experience in theaters. The spirit of Quad lives on.