You're missing the point and not for the first time. And you're doing it by ignoring mine.
You have to explain things in the context of the facts that objectively are known to exist.
Either Amanda is guilty of murder and staging a break in or she is innocent. If she is guilty, it is erroneous to discuss Amanda discovering the breakin at any time, because she would have staged it or at least had guilty knowledge of its having been staged. There would be no question of a guilty Amanda discovering anything, so all these ruminations about whether Romanelli's door was open or not are quite irrelevant.
Your contention is, or must be, even if you don't realise it, that a guilty Amanda, in full knowledge of everything murder related, including the break in and including the body, leaves her flat having just spent approximately four hours selectively cleaning it of evidence of her presence (Raffaele's too), but fails to clean the the bathroom and fails to dispose of the bathmat.
Then, with nobody knowing she is there except her co-conspirator Raffaele (Guede is long gone) and wanting to delay as long as possible the discovery of the crime, she leaves the flat and instead of simply slipping away unnoticed, immediately phones Romanelli to report 1) That she found the front door open 2) Blood in the bathroom 3) Feces in her toilet! She tells Romanelli these three things, but nothing else. Why? What can she possibly gain from this partial revelation? She has now succeeded in putting Romanelli on alert and cannot possibly predict what she might do. Romanelli could easily and reasonably be expected to a) Drive home immediately b) Call the police immediately. In any case, Amanda has placed herself at the crime scene and whatever else might happen, she knows it will be discovered and she will be identified as the first person en scene. And since, in this scenario, Amanda is guilty, then she will know that she must be a suspect.
So, leaving aside the fact that we know Amanda was aware of the evidence in the bathroom but did nothing about it, even though she could have, why did she contact Romanelli and not simply stay quiet and go back to pick up Raffaele and drive to Gubbio?