Changing the form in which something is presented isn't sufficient to deprive the original copyright holder of their rights. For example, collating the questions/answers from the test into a JLPT study guide would still be violating the intellectual property rights of the people with the original copyright. Changing up wording without introducing new/original intellectual content also won't cut it. For example, I can't take copyrighted articles from a magazine, do what amounts to no more than an edit/rewrite of the content, and claim the result as my own.
Getting away from the hypothetical: I have translated a Japanese novel and many people not familiar with copyright protections have suggested I should try to have it published. Problem is, I have control over what can be done with my English translation, but it is a
derivative work. The rights of the original copyright holder extend to derivative works as well. I own my translation and the rights thereto....but without the permission of the
original copyright holder my rights and my work are unusable. I only own my English rendition of the story....
not the story itself, which is something that transcends language.
Caveat to the above is that there are a very few "minority" languages (those with a mere handful of speakers) into which one may relatively freely translate and publish copyrighted material.
Further caveat: When talking about copyright, it is very important to understand that the word "publish" has a much broader meaning than we normally assign to it in daily life. It does
not mean "print on paper and slap between book covers".
Would providing copies of versions prior to this years be a copyright violation?
Yes. That would be publishing them, no matter in what form (physical or electronic) one did it. And there's even a caveat to that, of course, which is the "fair use" policy which may allow for limited copying under certain circumstances. I am not familiar with the details of that....but feel certain it doesn't extend to passing copies around on the internet.