This is a really nice looking set, and as a JIS-layout user I want to say THANK YOU for including R4 ろ and R3 む in the katakana sets. It makes a big difference :-)
If I could make one more recommendation from the point of view of JIS, an R1 ー (sometimes the line is inside a dotted box) key would make this perfect for JIS input. This key is the third key to the right of the 0 (one left of the backspace) on a Japanese keyboard, and is used to lengthen the previous syllable, as in キーボード (“keyboard”).
Proper JIS support on kana layout keysets is so rare that honestly I’m just thrilled you have the ろ and the む, so I don’t want to push my luck, but I did want to give you my input as an everyday JIS user.
Other than that, I love the red and gold colour scheme, and I think it would be really suitable for an urushi-themed keyboard I had in mind.
Thanks!