Albrecht Becker-Freyseng complained in his classic study Die Vorgeschichte des philosophischen Terminus 'contingens' (1938) that Boethius used 'contingit' as a dual-purpose translation of Aristotle's endechetai (it may be) and sumbainei (it happens) despite the availability of 'licet' for the former and 'accidit' for the latter.
Funnily enough, William of Moerbeke remedied this defect by rendering sumbainei as 'accidit' in his De interpretatione translation of 1268, but this version never gained currency – so much so that it still hadn't been printed by the time Becker-Freyseng was writing.
Becker-Freyseng would not, however, have been happy to see that Moerbeke followed the editio composita in using 'contingit' – rather than, say, 'accidit' – in his translation of Aristotle's phrase hopoteron/hopoter' etuchen (whichever/however it chances).