The script that helped me the most post-level 60 to tackle leech was confusionguesser:
Right after turning on this script I was amazed to discovered the sheer number of visually similar kanji that I never noticed before, probably because they are far apart in WK level. I would sometimes bring them all the way to enlightened and fail because I would confuse them with the other one.
But not just kanji, sometimes I would confuse the reading of a word with another word, but instead of having a fail and not knowing why, confusion guesser immediately point out the wrong word, and just knowing that information would let me understand why I confused them in the first place.
So anyway, confusion guesser is amazing at finding confusion that we didn’t even know existed in the first place, and by level 60 a lot of them have accumulated.