It was raining on the night of the murder. Stone is slippery when wet. The exterior of the cottage is stonework. The grass and dirt below Filomina's bedroom window was not disturbed. There was no evidence that Guede scaled the 13 foot wall. There is no evidence of grass or mud from below the window in Filomina's bedroom.
It's like the small bathroom scenario in the sense that there's no evidence, so tunnel vision is used to create a scenario around a piece of evidence. There is no evidence that Guede climbed in the window, but the alternative - that he walked through the entrance - supports that theory that someone opened the door for him. It also means that there is no explanation for the broken window.
Guede had no reason to believe that rent money, which is normally delivered to the landlord on the first of the month, would be in the cottage on the evening of November 1. Furthermore, he had no reason to believe that rent was paid in cash rather than by cheque.
It's interesting that we have to have Meredith sitting on the edge of her bed with her back to the door, oblivious to everything, in order to be a victim of a "blitz" attack. A blitz attack is not a sneaky thing, it is fast and furious - not quiet. We also have to forget that she was trained in Martial Arts and that she would fight with everything she had to save her life. There are no defensive wounds, but there are shallow cuts on her neck. Did she really just lie there and let someone cut her ... no defensive wounds? That is not who she was according to her father.