1. A computer-implemented method comprising: receiving (i) a digital representation of text in a particular script, and (ii) a label that indicates Unicode points that correspond to the text; generating a set of graphemes based on the label; for each grapheme in the set of graphemes: determining a set of candidate recognition units that form the grapheme; selecting, from among different recognition identification criteria that are associated with different scripts, one or more recognition identification criteria associated with the particular script; applying the one or more recognition identification criteria associated with the particular script to the set of candidate recognition units to identify a training set of recognition units that form the grapheme; and training a text recognizer to separately recognize the recognition units that form the grapheme, in the training set, in subsequently received digital representations of text in the particular script.
4. The computer-implemented method of claim 1 , wherein the one or more recognition identification criteria include a frequency of occurrence of a recognition unit in the particular script or a size of a recognition unit in the particular script.