So, after spending a disproportionate amount of time on FreeRice, I have to say that the vocab in the higher levels aren't necessarily always fair. Well, depending on how you choose to view the task. If it's a general English vocab test, it fails because of the historicity and obliquity of some of its words.
Words like animalcule and camelopard are only words if you've studied historical science/biology. Otherwise, there would be no reason to know (or use!) the words. Animalcules were first proposed with the discovery of microbiology to describe single cells. Camelopards are similarly archaisms for giraffes, what british taxonomists first thought must have been a hybrid between camels and leopards. The silly sods.
I don't approve of the use of those words (even though they were kinda my freebies to the next level), because they aren't an accurate test of general English vocabulary. Instead, it became a test of education -- who was a biologist, and who wasn't? Even historical words of British culture are a bit of a grey area. Yes, there is not such thing as language without context, and therefore any special vocabulary one learns must necessarily be registered in a specific field. The question is then how broad a field is it? Something like nosegay, what we now call bouquets, is a bit iffy.
Shakespearian words, on the other hand, I would be more lenient towards, if only because it's a "fair" education -- anyone who's successfully completed high school would have read and studied at least three Shakespeare plays, if not five. And words I totally approve of are "standard" in the sense that they weren't misappropriated names, like tintinnabulation, sesquipedalian, aphonic.
On the other hand, and this is something I can appreciate even if I don't approve, is that their one-word definition choices were sometimes a bit too limiting. Yes, a Paladin could be defined as a "champion", but I feel a closer cognate would be "knight". The emphasis is on the regality and chivalry rather than the victory. Similarly, I'd associate dusky more with a description of ambient lighting than skin pigmentation (ie swarthy). But it's usually difficult to find a one-word equivalent for the rarer words. Even though some of their options have been two or three words, most choices are singletons. So that point's a bit hard to appease.