of course the mistranslated latin is evoking the absence of a perspicuous possibility in language. A one to one ratio of a word and its meaning was abandoned long ago as a possibility with dictionary makers like Boswell, but Vodalus says something about the language they speak having only one meaning in one of his meetings with Sev, as if the future langauge they speak had finally achieved perspicuity. This creates a huge irony based on all the ambiguous and conceptually difficult events and ideas that severian presents, and creates an odd obviously mistaken linguistic paradigm for the culture of urth as well, completely disproved by the tale of the ascian and its multiple interpretations, though composed entirely of stock phrases.