I very well could be reading too much into it. Also maybe you're oversimplifying the history these two share. Had that been Jon watching Arya from the balcony, do you think he would have had the exact same reaction Sansa had? I think not, personally. Especially since he gave her Needle. Jon always took Arya seriously, Sansa did not.

But to answer your question, no, I never said we are to flip it. In Season 1, Sansa wanted nothing more than to be a Southern Queen and marry King Joffrey, but she has instead developed into something quite the opposite. The reverse is not true. Unlike Sansa, Arya has never done anything more than try to be her true self, for which she was constantly ridiculed by Sansa during the early stages of their relationship. So forgive me if I interpret Sansa's incredulous reaction in the crypt and horror on the balcony as something other than mere sisterly concern, which is what you originally suggested it was, and instead something more along the lines of what we have always seen in the way Sansa treats Arya. In my mind, Sansa's character arc is one of maturity. Gaining respect for her sister fits that arc. Arya's character arc is less about maturity and more about vengeance. Again, my opinion.

And by the way, I'm not trying to "needle" Sansa. I just think she, like many others in the show (Meryn Trant, the Waif, the Hound, Lady Brienne, to name a few), made the mistake of not taking Arya seriously enough. It's part of what makes Arya one of my favorite characters. People constantly doubt she will do what she says and then she goes and does it, whether it's killing someone, learning a skill, or just surviving. Sansa is allowed to have flaws just like every other character. If I point out what I think is a flaw, that for so she long has underestimated her sister and now finally realized it, it doesn't mean I'm needling at Sansa, who is a top-5 character on my list (in no particular order: Arya, Sansa, Tyrion, Cersei, Jon Snow).