I don't know what you mean by "reached the ledge". He clearly demonstrated it's possible to open the window and clear the glass while standing on the foothold below, then to pull up into the open window.
You said before:
I think you will agree he demonstrated fully how to get all the way onto the ledge by grabbing the bars. I think you would agree that if the bars were out of the way he would be able to do the same by grabbing the window frame and pushing up from the window sill. With the window open he would easily jump inside propping himself up on the sill like the person in the video, placing one foot on the windowsill on his way in.
I see no reason why Guede would have to brush off glass from the ledge to step inside. I think he piled the pieces of glass himself, clearing the window from jagged pieces before unlatching it, just like the person in the video demonstrated. Then he pulled himself up and inside, just like in the video.