Found this while looking for a checklist plugin for myself, but was terribly disappointed to find that it was outdated and @Magion didn't seem to have worked on it in half a year. So I took the liberty of forking and updating it myself. And since my game didn't crash running it (yet), I am happy to announce that I have successfully updated the plugin to KSP 1.2.2!
https://github.com/gobbo1008/WernherChecker/releases/tag/v0.5.0
I'll have to add that this is my first time working with KSP Plugins and that I compiled it against the x86 libraries (as I just realised), but I'm confident it'll work. ...maybe. Feel free to check out the changeset and correct me where I'm wrong!
No additional functionality has been introduced in this update, in fact, some may have been broken as I'm not 100% sure on a substitution I've had to make to get rid of all errors (specifically, Part.Resources.list.Find() was replaced by Part.Resources.Get()).
Edit: Yup. Resource amounts are definitely broken at the moment. Give me a moment...
Edit2: Nope. Seems to be a more complex issue unrelated to my substitutions. Going to have to read my way into the code a bit more to figure out where it's coming from.