It's an interesting point you make, but I'm not sure I'd necessarily agree with your choice of words. After all, alphabet is derived from the first two letters of the greek "system of letters" (to avoid being circular
), so hardly represents a modern concept.
More generally, isn't your concern based on the presumption that the world that Mark has created is just a thinly veiled copy of mediaeval England? As it's not, but a completely new fantasy world where magic exists, Mark could have made up completely new words for every single "thing"; but that would be hard to follow. So whether he uses "ale" or "beer" to describe the alcoholic beverage that people drink there is, to some extent, irrelevant, since the stuff is not necessarily the same as either Elizabethan ale, or a modern bitter or lager
I'd be interested to know what others feel - do you prefer language that relates a fantasy story to a period setting in the real world, or does the language not matter to you (except if it is inconsistent with the world described)?