Hello Tatsuo,
As Seishin-san says, and from my understanding...yes, the four samadhis are still intensively practiced in Japan. I have also met Gyosho Uehara a couple of times, a sennichi kaihogyo practitioner. In addition to hearing second-hand stories of meetings with the other types of specialists.
How is meditation practiced in Japan? I don't think anyone can speak for all of Japan or the West? Not sure where that kind of generalization leads. People do sitting meditation, walking meditation, mantra meditation, etc. likely it will depend on the the priest, temple and community. Some more than others. All priests learn them and some lay people learn them if they are interested.
Tendai has unique aspects but many are also in common with the rest of Buddhism. Meditations on equanimity, loving kindness etc. Dharma is dharma.
Some meditations will be similar to Tibetan Buddhist practices because Tendai has a vajrayana tradition. There are many meditations with visualizations.
The late Rev.Keisho Leary established trails on Mt.Cobb under the guidance of his teachers. Others and myself have done this practice weekly with him. If I recall, the path was about 12 miles around the mountain and took about 5-6 hours up and down a mountain isolated from human distraction and often without a trail. It could be called a 'ichinichi or han-nichi' kaihogyo. He had completed a 100-day practice of it and conducted twice weekly goma. The temple's focus was esoteric and outdoor shugendo practices as he learned under sennichi kaihogyo practitioners directly.
It might be hard to say what is "popular" in the West in regards to Tendai practitioners and practices or what that means...Tendai isn't in the mainstream like other traditions. For myself, and a few of those I know directly, we are very interested in the practices of mantra, goma etc. Some others are of course more interested in pure land, shikan, scholarship, Lotus sutra, etc. From all the foreign priests I have met thus far, each has had their own entry into dharma and Tendai specifically. If you have a particular interest there are a few Tendai priests here who can point you to someone of a similar interest! Something I appreciate greatly about Tendai practice is that it can accommodate a lot of types of dispositions and practices!
This is all my experience and opinion of course, it would be impossible to speak for 'Tendai' or a country...
gassho,
Myoei