I've updated the code in GitHub and created release 2.3.1. I've tagged it as a Pre-release for now. It might take a day or so to test it out. If you want to try it, you can grab it and install it manually.
Just download TradSimpChinese_2_3_1.zip
https://github.com/Hopkins1/TradSimpChinese/releases
Edit - Plugin now is (or soon will be) available via the Calibre plugin update system