Hello from Wisconsin,
I visited both exhibition sites in September. They were in Brno at an exhibition area west of Brno center, and in the Municipal House in Prague.
Before I left Wisconsin, I had a very hard time locating where and when these paintings could be seen. And I just now went to the Much Foundation link a previous responder provided. I could not find a date on the Much Foundation statement that the art was going to Tokyo. But it seems to me the paintings were in Japan before they came back to Czechia.
The person who responded saying that the exhibit in Prague had just ended sounded reliable. I don't want to knock the Mucha Foundation, they did find locations for the 20 huge paintings for last fall. Bravo, they are so large finding a place for even half of them was no doubt a challenge. But their inability to provide location and ticket information or have post cards or posters available for a NO PHOTO event shocked me. (Such an easy way to raise money)
The Brno location was the better of the two for displaying and enjoying the art. If still there, it is a simple train ride from Prague to Brno and costs about $9 one way. The TI where you can get the exhibit tickets is outside the train station. The tram that would take you to the exhibition hall is across the street from the train station and TI. And while in Brno, enjoy a walk through the city. A good entry point is opposite the train station and along side the grey Kentucky Fried Chicken outlet across the street and a tiny bit to the left from the train station. You can walk that street one end to the other and see a lot of the old town.