Simple answer:

It is a badly coded mess of spaghetti code, written with an ancient framework (AngularJS, currently running version 1.5.15), then ported to different platforms with Electron.

Have a look at the source code in your browser, it is not obfuscated in any way.

It is a single file of almost 17MB (!) of minified JavaScript, and I'm surprised the browser doesn't outright crash and actually manages to parse this, run and display a web application.