It is often noted that Chaucer's spelling was wildly inconsistent: Cunt, if you will forgive an excursion into crudity (as we so often must when dealing with Chaucer), is spelled in at least five ways, ranging from kent to quainte. So it isn't possible to say whether the inconsistency lies with Chaucer or his copyists or both.
Bill Bryson. The mother tongue
Bill Bryson. The mother tongue