光栄 - こうえい - honor
栄光 - えいこう - glory
just kiddin’, I have no idea! 
Something, might? be gleaned from taking a look at the Most Incorrectly Answered Kanji/Vocabulary - #4 by ekg thread?
Which makes me think there will not be much “accumulated” data really. As the WK-team has a habit of making updates weekly for things being suggested, and improvements they’ve been working on for long-term keep-up for the site. But there are items being block listed every week for example, so yeah, that changes the statistics you can gain long-term of which items are failed and why! (before or after weekly changes). 
You’d have to post the questions directly to the Tofugu team likely and if they have some other means of measuring impact of their changes on the site.