First of all, I want to express my sincere gratitude for posting your question. Because of you, I downloaded the catalog from the website, and although it took a very long time to load, it was without question worth the wait. That catalog is stunningly beautiful. It's also full of good information in both Japanese and English. I think I have one piece of Kutani ceramic, and I have a much greater appreciation for it now!
You can download the catalog here:
九谷焼総合カタログ(K7) 【通販サイト 九谷焼 鏑木商舗】九谷焼の伝統を金沢武家屋敷から世界へ
Just be aware that it will take a lo-o-ong time to load (as in something like 10 minutes).
Anyway, I have another link that may or may not be of use to you. It's worth a shot.
Finally, you could write them and send your question through snail mail. That way will take a while, but it's pretty much a safe bet that your question will get to them.
Good luck!