If a creature can see through magical darkness, and if the curtain is within the range at which they can do so, then yes, they'd be able to see through it.
Did you? I'm afraid I never got an e-mail notification about the comment (or at least I don't remember seeing it). LiveJournal has been a bit funky lately about sending those out.
From post 86 of this thread.Mouseferatu said:Yep. It "floats," in that you need not choose in advance which mystery you're going to use it for.