Briefly, I have a question.
What is the proper course of action when a friend (Y) tells you (Z) that she (X), who you’ve always considered a friend after you had trashed the crush you once had in the interest of a deeper bond, had become coy as a reaction to your friend’s (Y) question, “So what’s the deal with you (X) and him (Z)?”
[Updated to clarify whose role is what. Thanks, Eric!]

Is there a friend A and friend B here? I think I’m a bit confused. I think I understood it better glossing over it.
My advice is stay the course. Sound the depths. Wait for another development. I’m passive like that, though.
Much better! The “she” is the confusing part. My advice stands. But be excited!
up the flirting slightly and play it by ear. if you think she’s interested, she probably is.
Must run in the family, this being-ambiguous-about-amorous-developments business… ;)