"Knowledge" is just a word. It references many different concepts.
> In the real world it is impossible to find human experiences that are "causally linked" to facts in the world
Either you've misunderstood what causal linkage is, or else you are some odd brand of solipsist, but either way, this is incorrect. Causal linkage just means that that event participated in causing this event. The sun being in the sky is causally linked to me believing it's day time, for example.
> And yet, most of us would believe that there is a difference between looking at a broken clock that says noon, versus a working clock that says noon.
Of course there is. In one case, your belief is causally linked to fact. In the other case, it isn't, but still happens to be correct.