Is there any way to drag the end of multiple tracks in Adobe Animate? I've tried every key combination I can think of. It did not capture in the screenshot below, but there cursor was the double ended arrow used for dragging, but I can only get it to drag one track at a time. I have the "Edit Multiple Frames" mode on.
The double arrow cursor you saw is for stretching motion tweens. It would scale the placement of the keyframes in the tween. It only makes sense for one layer at a time.
If you just want to extend a set of layers to a later frame, say 1190 in your example, you could click in the first of the layers at 1190 and drag downward, so that you have the 6 layers all selected on an empty frame at 1190. Then press F5, and that will extend all of them in one go.