Times have changed and far more often than in the past Japanese developers are making things easier to get games ported. That's things like easy systems to insert new text into the game code, keeping their source code properly backed up (a common problem in generations past was lost source code) and a general more global market themed mentality. In a lot of cases Japanese developers have someone who writes up basic notes for what would need to be translated into English so that if a publisher is interested in releasing it overseas, they already have a decent idea of what kind of effort this would require. Now, this isn't always the case, there's still companies hard coding Japanese text into games and losing source code. But this situation has improved drastically in recent years.