Pieanne,
No. I still think that "how" means something different from "how come" (the equivalent of "why") in that sentence.
Example: The sentence below doesn't ask for information about the
methods of translation. It asks you to recall an incident or
event. The intent is to elicit an affirmative - a recognition of
the incident or event - with the further intent to speak at greater
length on the subject once the questioner has oriented the listener to
the topic at hand.
"Do you know how I translated some material from French a few months ago?"
So the "how" means neither "why" nor its equivalent "how come".
In fact, "Do you know how I ...?" means "Can you recall that I ...?" or simply, "Recall that I ...".
CJ
(I hope I interpreted your last post correctly in my response!)