I doubt anyone has found a source for Kouki wood in the US. One problem is that it is endangered; the other is that Kouki is a Japanese name. A cross reference for wood names would be helpful, perhaps in the “Learning Center”. Along with the Japanese common names, Chinese and Western names should be included. The list should be based on the botanical name, since common names are often applied to multiple species. Here’s some inputs:
Dalbergia luovelii: (China) lushi heihuangtan, hei suanzhi, (large-leaf) zitan; (UK/US) Rosewood
Pterocarpus indicus: (Japan) Karin; (UK/US) Amboyna
Pterocarpus santalinus: (Japan) Kouki; (China) tanxiang, (small-leaf) zitan ; (UK/US) Red Sanders, Red Sandalwood (NOTE: not to be confused with genus Santalum, aromatic Sandalwood)
Pterocarpus soyauxii: (UK/US) African padauk, African coralwood
Mechanical properties such as strength and hardness might be added as well.