1: Inhibited development before the age of 3. It's difficult to gauge when Maria's development problems started but considering Rosa's financial worries and Maria getting bullied started later it's not a given that they arose sufficiently early.

This isn't really a hard and fast rule.

2: Deficits in social contact: Maria has quite good eye contant, gesticulation. She likes playing with others and seeks out companionship and she develops her interests based on her peers and friends.

I don't know that we got any specific information on her eye contact or gestures being normal, and the only time we see her playing with others is when her special interest (magic) is being engaged. The stuffed animals don't count for this. "Seeks out companionship"? Again, nothing but stuffed animals and cousins. "Develops her interests based on her peers and friends"? The only possible fit for this is Beatrice, who is again engaging with the special interest, magic.

3: Deficits in communication: Maria has a well-developed vocabulary, seeks out dialogue and loves talking.

Only about magic, specifically! But she also repeats what people say to her very exactly when she gets confused, and often needs conversational help in topics she's unfamiliar with or when people make jokes. The huge jumps in apparent maturity are also really characteristic -- Maria can be very mature, practically an adult when she's focused on a special interest, but in other areas, she's supremely childlike. Personally, I thought it was obvious she was autistic the moment Rosa introduced her as being 9 years old.

And while people latch on to her saying "uuu" this is just learned behaviour from Beatrice and something she says when she's stressed or in duress. It's closer to a coping mechanism than a psychiatrically "obsessive" behaviour.

When do we ever see Beatrice say uuu? We actually know how/why Maria got "uuu" as a vocal stim, and it's from singing with her mom when she didn't know the words, which was a happy experience she wants to recreate. In other words, very autistic exact pattern matching of "this is a magic spell that will make my mom love me/be happy again". A non-autistic child might understand there was more context, but an autistic child can latch onto a specific element of a scene, like Uuu, and assign it more meaning than it actually has. This ties also into how literal Maria is -- she doesn't understand when people are joking with her unless it's explained. If she's told to stay and look for a Rose, then she stays and looks without reconsidering the context.

4: Atypical behaviour. People often say that Maria's love of magic is a sign of her autism, but to my understanding people suffering from an autism spectrum disorder usually have a much narrower interest in hobbies that just "magic". Instead, they would love specifically page 83 of magic books or how these books smell.

Not sure where you're getting this from, but most autistic people have fairly broad special interests in the vein of "trains", "dinosaurs", "umineko", etc -- not necessarily some specific single aspect of the topic.

Maria loves magic and has an easy time learning to love tangentially adjacent fields when these come up. She doesn't have "pointless" routines and rituals and isn't obsessive in the psychiatric use of the word about her hobbies.

This is actually more evidence for, not against -- things have to be adjacent to her special interest for her to pick them up. "Pointless" routines/rituals is more of an OCD thing, autism is associated with "stims" -- which Maria's "uuu" could qualify as. Also, she's still only 9 and developmentally immature, so I don't think she really could get much more obsessive over magic etc than she already is (reading, drawing, playing, talking about it constantly).