It's quite hard to understand the written language of Zelda. But some of them, you know what it kind of says, but hardly any information.

And I agree that it is Katana from the language of Japan. Hiragana has too many curves in it's alphabet, but Katana has more straight lines in each symbol.

It would be cool if Hyrule had it's own language to interperate, but I don't think it's like Lord of the Rings, where JRR Tolkein made his own unique language in the books.