I was also struggling with the synonyms. I don’t know when you used KW last time, the latest update improved the situation a bit by showing you item you got wrong sooner, instead of producing one giant heap of synonyms you mix up all the time at the end.
I can also recommend a small script, it turned KW from frustrating to fun (although a little cheaty). It shows a blurred solution, so you can guess how many characters are in the solution, kanji/kana, shape of the kanji (should it be 人殺し or 殺人/殺人者, …)? It certainly improved my KW experience.