Thanks for joining the project and sorry for the confusion.
The HHKB caps are fully compatible with the keyboard you ordered. The only note is that HHKB style split right shift is not possible because the barrels and PCB pads are in physically different places. Not to worry, most HHKB folks will go with the JIS style split right shift instead (1U+1.75U keys in the right shift area instead of HHKB style 1.75U+1U), or choose to have the regular 2.75U right shift while using all of the other HHKB style functionality such as swapped Caps/Ctrl and maybe split backspace or regular backspace, and the delete/backspace key being the 1.5U key to the right of the ] } key. There are many options to choose from. You can even order the HHKB Front Printed add on set if you prefer the efficiency of the HHKB layers.