Do not delete or post in.

Trade secret. I can tell you that all you need to do is change the filenames in the the US NBL to match the Japanese ones
(_J rather than _AE), and that there's a fairly good explanation of how NBL files are laid out on the psumods archive wiki.
Use nbl -d to get the file blob uncompressed so you don't have to entirely rebuild the file manually.
You'll still need to blank out the compression and encryption information.

You have to make the game accept it.
There's a checksum on it, and the patch server will update both the checksum and the text back to the original when you log in.

Well, I'm sure it could be made to suit the crc, but I haven't figured that part out (why bother, my purposes are adequately suited by other ways).

Hucast:
Excalibur 100/100/0/0 - have
Excalibur 0/0/100/100 - need


Racast:
Yashminkov 3000R - need
Nug2000 bazooka - need
dual bird - need


Fonewm:
mother garb - need
Gimerge - need
Ramerge - have
Summit moon - have