I’ve installed a new instance of hitechbunny’s server and updated it to correct errors (API url had changed), and also posted a new userscript: Shin WaniKani Leech Trainer
Basically, I use this a lot, and having it not working is Not Good for my studies. I just deployed their code quickly to a free heroku instance and changed the URL in the trainer script and my very basic, still-at-work testing indicates it’s doing okay.
Disclaimer: I know nothing at all about Go which the server is written in, so there might be proverbial colliding with spinning blades and I wouldn’t know at the moment.
Anyway, give it a shot and see what happens.