So it would appear that I personally made a bit of an oversight concerning the ISO keys back when the set was being ordered. Several people at the time were complaining that none of the available R3 ISO keys in the set would match the rest of the set with sublegends. I talked with GMK about it, and given that the |\ key is the only one with a sublegend, I was given the choice to change one of the other R3 keys with that one for no change in set price. As I didn't realize that some ISO layouts actually use both of the keys, mostly because there are lots of sets that only give one or the other, I figured that would be the right choice to give those complaining the chance to use a wrong legend key to get the sublegend, and(incorrectly) thinking that "normal" ISO users would be unaffected by the change of keys. What compounded the issue was that, between dealing with the MOQ issues of the child kits and the largest number of invoice-dodgers in a buy I've run to date, I apparently never posted the updated mockup I was given that showed this change so no one else was made aware of the change.
I do sincerely apologize for these oversights and the effect they've had on those who have bought the set who needed the missing key. I will be getting in touch with GMK and seeing if there is any way that I can possibly get ahold of some of the missing key in order to send to the affected ISO users.