Yes, and the younger you are the easier . I think the pinnacle age to efficiently learn new languages is 21, after that it becomes difficult.
I think it is a bit hard to slap an age on that. It is definitely true that the younger you are, the easier it is. 21 isn't that magical age where your brain suddenly just shifts and stops taking in knowledge efficiently. 21 is usually the age where people fully enter the workforce, and when they finish college. After that, people rarely get the chance to exercise their mind the way formal education does. You usually know how to do your job via training and after that you tend to stop learning things outside of the skill set you need for work.
With formal education, you're forced to learn or fail, so your mind is usually in the mindset to retain knowledge. As long as you exercise your brain, you can really learn as much as you want for as long as you wish. Age will definitely begin to hinder that growth down the line, but I wouldn't say 21 is where it gets harder. If anything, It'd be closer to middle adulthood where you find it slightly harder to retain information because your body is entering the downslope of growth.
I am inclined to agree with everyone about SE not bothering to fund the dub in other countries due to fearing a loss of money. But, wouldn't boycotting it, like you seem to be dead set on doing now, only do the opposite of what you want? I mean I have never boycotted anything before, but I don't know, you seem to think not buying the game will change their mind about translating it when people not buying the game are the reason they aren't translating it in the first place... So it would be counter-productive? Maybe? (If I am way off base here, I apologize)
I would be more inclined to agree with what Spock said and to try and show Square that you all do car, and that you do want this in your language. And if that doesn't work, then an online guide made by fans is a decent alternative. I am not fluent in Japanese, just as you are not fluent in English, yet I know enough to get me through the basics and I have enjoyed many Japanese games. I mean that is just my two cents...
This, all this.