“Where are THOSE long skirts?” does not really make sense in English. “Those long skirts” implies that you can see them and therefore already know where they are. If you went into a store, you would ask “Where are THE long skirts”. Sorry to be picky about the English. I am really enjoying and appreciative of the Czech. Thank you.
It is entirely possible to say that - albeit rarely. If you are the merchandiser in a store and you loaded up the inventory in the truck, yet don’t see them now when you are sorting through what goes where, you would ask your assistant, “where are those long skirts” (the ones I saw earlier).