I think that she has ability to strongly visualize letters and words. For most of people is hard to imagine one long word perfectly(I mean with all letters at once). Try to visualize a word ‘synesthesia’, the whole word as single image.
This girl see this, 10 times clearer and faster. She has problems with other alphabets, because she isn’t used to it. Her ability could be developed in the childhood. She used to read a lot in the young age, therefore her ‘word imagination’ had much time to improve.
I also believe, that she subconciously imagine sentences, in a different backgrounds. It would be real places as well as imagined. She kind of write in the images in her mind. It’s how people remember informations, however the most of them is not aware of it.
But there is one important condition for this type of recall. It requires absolute focus on reading.