As I said, I don't believe that "perfection" and "imperfection" as used by the WT are Biblical concepts at all.
I think "imperfection" is just an original (cultic) rephrasing of the classical Christian dogma of "original sin" (which btw is not identical to the uses of the word "sin" in the Bible). I fail to see any true conceptual difference between the two doctrines. The WT version is just shallower as usual (the same could be said of "ransom" vs. "redemption"). "Imperfection" sounded as a more modern and apparently understandable word in the technical age of the late 19th and early 20th century. Religious concepts reflect the time of their creation.