I think the last time this happened was when SRW Alpha Gaiden was translated. I have a friend who's been working on this, so I've been hearing about the process as it happens. Apparently there was some kind of large-scale effort to call this whole project a hoax, for example. It's not a hoax. I played it in beta, it's there for you to play right now. It exists.
Anyway, SRWJ is probably the best of the Game Boy Advance SRW games that aren't Original Generation: they have licensed robots like Mazinger and so on, so the likelihood that they'll ever come out in English (especially as the GBA is a dead platform) is basically nil. A large amount of the material that was in J was chopped out and placed into W, the first SRW DS game. Despite lacking Voltron, J is a much better game. It has cool stuff like PUZZLE ROBO, in which the player solves an SRW chess problem in X amount of turns. Give it a go, especially if you're snowed in like I probably am for the next couple days.