If you don’t already, consider running a jisho search or using the wk search box to look up your wrong answers. For jisho you can limit a search to kanji, ex. kou #kanji. Doing something like this (or using the scripts) really helps me find out why I make certain mistakes. Given your pace 200 apprentice items is really high. I like to peg my limit to around 150% or 200% of 4 * Daily Lessons. Either way, with that much churn I’d suspect a lot of the leeches are probably similar words that can be hammered out relatively easily. This might also be a good time to take another look at tricks like tofugu’s guide on rendaku rules and so on. Best of luck moving forward, I’d agree that clearing the apprentice pile and tackling the leeches are a great thing to do.
If you’re open to third party tools and just don’t like the idea of userscripts messing with browser pages Flaming Durtles (probably the other apps as well) has a self-study quiz option that’s really robust and includes leech filter. Alternatively, I think I_I is using his own modified version of BishBashBosh here which I think works with a read-only api key. Worst case you could always add troubled items manually to an Anki deck or physical flash cards to review. Either way, doing a little bit of leech review weekly would probably help to stay on top of things moving forward.
Leeches are serious pitfall with WK. It doesn’t have any tools to deal with it on its own, so it kind of pains me to see such a strong association that scripts = speedrun or scripts = bad mentality on the forums here. If you ever change your mind, check out item inspector. It has a nice leech filter and table view that I think makes it easier to figure out why certain words/kanji are become leeches in the first place. Extra shoutouts to confusion guesser and the niai visually similar kanji scripts for helping with that.