Sure you can use OB-Xa in KK but it's not properly mapped and none of the presets are recognised yet. If you save any patches they'll fall under the user section which isn't ideal.
NKS is far from ideal.
The fact, that it actually does'nt recognize any original presets but only speciel NKS presets is far from ideal.
NKS also can't recreate preset systems like Arturias, where Analog Lab and the individual applications share presets.
And NKS presets can't be used in the original applications.
The only reason i can see NKS seperate user presets from others is NI must get royalties or something like that. It's not to be user friendly, as it as you say is'nt ideal to seperate the user presets.
Perhaps NI should be asked about changing that?