Why use TypeScript?
Don't overcomplicate things. Use ES6. If you want imports/exports - bundle app with rollup.js, if you need to support old browsers and transpile code to ES5 - add polyfills you need and use babel plugin for rollup. Don't need to use Babel itself. That's all, everything is very simple and you won't have any problems writing your code and debugging.
There are lot of IDEs with ES6 support and ESlints to help you, for example, not to forget to pass all the required variables into function and will provide a nice error during compilation.
Also use doc comments and this will give you a warning whenever, for example, you will be trying to pass a String into something expecting a Number.