Rosetta Stone interpreter for DS, possible?

You know what would be a great homebrew for the DS, well in my opinion at least. A Rosetta Stone interpreter. For those who don't know Rosetta Stone, it's a language learning software that teach by immersion. You can learn pretty much any language with it and it's pretty simple, it show you picture and you need to click on the right one. Soem part of the program would be pretty hardto do on the DS, like voice recognition and thing like that but even without the fancy feature, it could be quite useful! And as long as you don't distribute it with the language file it would be legal I think.

It would take a long time to work such an excellent program out but in the end it would save a lot of people.

Problem here is that it has to be a Rosetta Stone-like interpreter to prevent legality issues and whatnot. People already with flashcarts could skip buying the actual program and pick up a homebrew version for free.

But then again, there have been a bunch of other free versions of other programs. But these aren't up to par with the original copies.

Perhaps making language teaching homebrew stuffs instead? I dunno, I just can't see Rosetta Stone being transformed into a DS version successfully without causing some problems.