The knowledge skill for each active skill is going to be a problem, I mean, most runners usually have a few knowledge skills pertaining to their active skills in some way. But that doesn't mean that the active skill means they're lacking in knowledge of what they're doing, they just don't know extensive background and design notes about everything they handle, or where they could buy replacement parts or something like that.
Like, for instance, my character's background was that he was raised in captivity by MCT to be part of an infiltration and investigation group, I'd be the guy who could speak most common languages to better interrogate people, and my active skills include compelling them to do what I want, and the ability to erase their memory, better than having to just kill the guy. In captivity I liked to listen to music, or try playing my own, so I have knowledge in NeoClassical music, and even a small skill in playing the synth link. But that doesn't mean I don't know what I'm doing when comes to talking to people, or using "spells".
But for someone who has a high attribute, and can just pull something off, but is defaulting on the skill, that would be more in line for what you're talking about not having knowledge of what you're doing. They aren't trained or knowledgeable they just kinda figure it out.