Once you realise that pedantry isn't part of the gameplay it gets a lot easier. It merely has to be good enough for those sitting at the table - who themselves are also invested in their suspension of disbelief.
> effort worthy of a major novel or movie
That's the thing, RPGs do not exist in a vaccum, nor are they trying to portray a particular historical era realistically - they are based on fantasy novels. That means you don't have to ..
> understand what a medieval blacksmith understands
... you merely have to make up what the minor character of a blacksmith in a Jack Vance novel might say. If you want to do some common tasks there is probably a table for armour repair or weaponsmithing costs in AD&D 2nd edition somewhere.
There's usually a bit of tension between railroading the players into set-pieces versus dropping hints and relying on them to cooperate, but that can be all part of the fun.
> consistent
Consistency issues can usually be fixed with wizards.
(edit: the whole issue is addressed by Shakespeare at the start of Henry V, "can this cockpit hold The vasty fields of France" etc)