Those book have a very japanese feel. So if you are more interested in chinese/india/korean feel, you should look for other publisher (there is chinese book with a beautiful scantily clad woman on the cover and a good monster book from green ronin, with some wild CR/skills but no errata).
The monster of rokugan book is useful to anyone, even people unfamiliar with Asia (contrary to Jade Dragon & Hungry Ghost from Green Ronin).
The magic of rokugan book has the strongest tie with the Rokugan book, it's main part is new spells for shugenja and unique magic items (so half of the book is immediatly usable, the other half needs some adaptation). It also has some generic prestige class (ghost hunter, master smith). The biggest problem will be spell and magic items that use the taint or honor mechanic, but there isn't many of those.