I think teleios and teleiotès carry very different meanings according to the texts and the specific kinds of "Christianity" they come from. For instance, your definition
Most of these scriptures do not refer to perfect people or perfect behavour, but coming in to a more complete understanding of what Christ has done for us. If we look at this as full grown and complete rather than perfection, I think these scriptures make more sense.
suits very well Pauline Christianity.
But when you come to Judeo-Christian theology, such as is echoed (diversely) in Matthew or James, the emphasis is quite different -- since in this perspective the only thing Jesus has done is revealing the right interpretation of the Law.
For this very reason, I doubt that in the Matthean context the answer given to the rich man is sarcastic (cf. 5:48 where "perfection" of love is what is seriously asked from Jesus' followers).
The more Gnostic accent of Johannine Christianity and the Alexandrine allegorical interpretation of the Jewish priesthood in Hebrews give still other shades of meanings to the word.
Once again, neither of these NT ideas is correctly reflected by the WT doctrine of "original" or "final" perfection of Adam and Eve, Christ or mankind.