How did you compose the Latin? It seems... not very classical both in word selection and grammar. For example,

    /* Est c consonans (non vocalis, non spatium, non littera non-Latina)? */

seems a word-by-word translation of English words into Latin words ignoring the structure and syntax of classical Latin. Perhaps it ought to be something more like:

    /* Estne c litera consonans (neque vocalis, neque spatium, neque litera linguae aliae)?

edit: On reflection, notes on the return values of boolean functions probably ought to be some sort of utrum ...an construction.