Was the use of ANN necessary, or simply done because it was cool to do? Because at least in my mind it looks like extracting the text and running a brute force program on it would be faster, no?
If my reading is correct, the neural network was used to OCR the image, extracting the text. From there, it is indeed a simple brute-force string search.
The use of ANN was completely unnecessary, as there are only 3 characters in the crossword puzzle. I wanted to try out the OpenCV ANN implementation though and since it's not a real world application it doesn't really matter.