Sometimes entering a different synonym or quasi-synonym during the quiz results in it saying to try again using a different word rather than failing the question on spot. Do we have any control of that? I have trouble differentiating between ぎっしり and びっしり. They seem interchangeable most of the time (and in their English definitions only the presence of the second meaning for びっしり gives any hint which is which), so I think they it would be reasonable to handle them that way too.
If you enter a wrong answer that you think should be a synonym during a quiz, click the ? button at the top of the screen and "Report quiz error". Choose the option "My answer was also correct", and if it's also valid based on the hint an exception will be added.
