For my brick facade, the windows are recessed and allow me to insert 2 boards that are perpendicular to the window and slide into the recess in front of the windows. I run screws through these boards in "into" the bricks. Although, they do not penetrate the bricks on the house, it creates enough tension to hold my prop in place.Wow... I think this post may be what I've been looking for. My house has a brick face and I've been struggling with how to board up my windows without drilling into the brick.
That said..I don't fully understand how you have these things attached to the screen tracks. I see the bar angle screwed into the board, but what holds the bar angle in place? Any additional pictures or details you can provide that can help?