All of their other examples seem to start with diacritics as well. What a mistake!
a) The search space is limited with human-supplied options.
b) The output isn't deterministic, is offers a series of best guesses.
I would say this is closer to a NN-powered spellchecker than an authoritative source on the restoration of the work. It still requires a decent amount of interaction from an actual expert for the system to work.