The recent NoA 3DS press release confirms the Western name of the game, as well as a fall 2017 release window for North America.
☆ NintendObs Weekly – Monday, June 19, 2017 – Sunday, June 25, 2017.
…Wanna play? Buy a 3DS.
And if you’ve already got yours, click on Layton’s Mystery Journey for everything you need to know about the game. 😀