Interesting. But isn't this a form of 'transcendental realism', though? — boundless 
This is what I mean by different theories.
The Kantian system of knowledge 
a posteriori, is twofold: sensibility, arrangement of the given, and, cognition, the logic in the arrangement of the given. The logic of the arrangement is determined….thought….. by the tripartite coordination of understanding, judgement and reason. All that which is produced by logical thought alone, is grounded in principles 
a priori; all principles arise transcendentally in pure reason, therefore the concept of “real” in transcendental logic is inappropriate, instead subsumed under the primary condition of logic 
writ large, which is correctly called “valid”. From which follows the notion that “transcendental realism”, is self-contradictory.
An alternative epistemic theory may be predicated on transcendental realism, but not within or even implied by, a Kantian system, but rather, by re-defining the predicates of an established method and/or constructing different relations between the components of that method.
Such is the fate of metaphysics in general: a guy adds to a theory in some way, shape or form, then accuses the original of having missed what was added. It may just as well have been the case it wasn’t  missed in the former at all, so much as rejected. So the new guy merely cancels that by which the original rejection found force, and from within which resides the ground of accusation of the missing. Even without considering your particular instance of this, it is found in Arthur’s critique of Kant, and, ironically enough, Kant’s critique of Hume, a.k.a., The Reluctant Rationalist.
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…..it remains the case no human is ever conscious of all that which occurs between sensation and brain activation because of it…..
— Mww
On this, I agree. That's why I think that our knowledge is imperfect. — boundless 
Dunno about imperfect, but even if it is, it has nothing to do with being unconscious of some operational segment of our intelligence, in which no knowledge is forthcoming in the first place. Perhaps you’ve thought a reasonable work-around, but from my armchair, I must say if you agree with the former you have lost the ground for judging the relative quality of your own knowledge.
Contingent, without a doubt. Imperfect? Ehhhhh……isn’t whatever knowledge there is at any given time, perfectly obtained? Otherwise, by what right is it knowledge at all? If every otherwise rational human in a given time knew lightning was the product of angry gods, what argument could there possibly be, in that same time, sufficient to falsify it? Wouldn’t that knowledge, at that time, be as perfect as it could be?
The system used to amend at some successive time the knowledge of one time, is precisely the same system used to obtain both. So maybe it isn’t the relative perfection of knowledge we should consider, but the relative quality of the system by which it is obtained.
And we’re right back where we started, re: any system in which a part is missing must be imperfect.
Do you see the contradiction? What would you do about it?