It's good to keep your feet behind you as a general thought, so before teaching an intermediate to "pull back your new inside foot" for simplicity sake just tell them to keep their feet behind them. This promotes ankle flexion of both feet.
I have heard a trigger cue stated of pulling the heel back into the heel pocket. This flexes the ankle. Perhaps this is a smaller movement than others are describing, but it's very effective.
I agree. My point here is that focusing on standing on the old inside ski as early as possible in the new turn brought about "being centered on the old inside ski" more effectively than focusing on "foot pull back." The pull back happened automagically without focusing on "pull back", but instead focusing on "an earlier lateral weight shift."You need to work more on this. Short turns, by pulling the inside foot back, you are ready immediately to start the next turn because you are centered on the old inside ski.
And there's no reason why you can't flex the inside leg while pulling it back.