It's far from an invention to this RP... The Manga tells us it's a KG <.<" I'm just trying to rationalize everything so it makes sense to me because the whole "It's that way because we made it that way." isn't a good enough reason for me... Unfortunately I have a habit of needing things to be a certain way, I blame my OCD but others could call it ignorance or something along those lines.
The manga definition of a KG is an ability restricted to the bloodline of a clan. These CE are in no way restricted to a certain bloodline, and are therefore not KG. Elemental combinations are one way a KG may manifest itself, but there's nothing specifically stating that's the only way to get elemental combinations. For instance Roshi is able to use Lava due to being the jinchuriki of the 4 tails. His use of lava isn't a KG as its not restricted to his bloodline, yet he's still able to make an elemental combination.
So, as you can see, the use of elemental combinations is not restricted to KGs.
If that's still no good, I don't know what else to tell you. You may not like how its worded or whatever, but its not going to change just to accommodate you. You'll just have to get over it I suppose.