Getting a ruleset translated into your own language is always nice, so congrats to the Japanese gaming community. And good job on the translators side of things!
With gaming space in Japan being even harder to find than in other countries, I believe that "Frostgrave" could do really well. You really don't need a lot of room to play on, and you don't need many models either. YOu still need some room for all the terrain - but that's the same with most other tabletop wargames too.
On top of that, "Frostgrave" is easily adapted to all kinds of settings, and already comes with a bestiary that covers quite a few "typically Japanese" creatures.
So yeah, the game could do well over there. Now its chances have become even higher!