Klaus is supposed to be THE maker of magical artifacts just with a rather bizarre twist. If the White Council had gotten the Eye then the likely would have headed the team investigating it. The closest to a human Swartalf in ability.
He isn’t an Alt Kringle, more a blend of Gepetto and Robert Oppenheimer, which is why Jim wants to write him, but why there is little opportunity in the narrative to do so. That why I suggest a Kringle pov story, they must know each other professionally, and we have not had many non-human pov stories and some insight into Vadderung would be nice.