They do use an algorithm that will mark things correct even if you make a typo, assuming it’s close enough to the correct spelling (I’ve completely butchered the spelling of words before from typing too quickly but still gotten it marked correct, I believe the more letters in the correct answer, the more leniency from the algorithm)
I recommend installing the Override Script, you can ignore incorrect responses and be given the opportunity to put the correct answer/spelling next time around without affecting the SRS for that item
Also, you can include synonyms for some words in your reviews if you want, there are lots of ways to make your experience here on WK work for you! 