when ana saw herself in the apartment across the street

To me, that augmented the message of Ana yearning for powers in a world where she was so painfully powerless (to have prevented her mother's death) ... She'd already convinced herself she had the power to avenge her mother by thinking she was killing her father (and later thinking she could offer that service out of compassion to Abuela and also in revenge to her Aunt) ... but the scene you raise came after that first "poisoning" power she imagined she had to let us see that her yearning for power wasn't just limited to "crime and punishment" but also her craving to be able to fly from rooftops and resist the rigidities of gravity ...