Good job finding that out, I hadn't noticed it before
Since it looks like a direct sequel to Katekyo's chapter 4, it makes sense to translate that one too. About the other stories on Katekyo (the book)... what Hage said. From chapter 6 forward things become waaaaay too weird for our tastes, so we don't really plan on doing them.
PS: For some reason they changed her name from Yukiko to Yutsuko, on the link you posted... but it's definetly related, so it must have been a slip on Kenji's side, or something.