> I don't understand why this is written in Typescript

I suppose you're not very familiar with typescript then.

Listen, all this CLI app does is serve as an interface to send requests to the Cloudflare API. This means it only does things like sending HTTP requests, and outputting JSON. The cli app also needs to run on multiple platforms. Performance is not an issue or a concern.

I'd frame this the opposite way: what better tool do you think there is for this purpose other than TypeScript?

On top of that, there's the fact that Cloudflare's core services run on V8. If there is anything this company has, it's people familiar with JavaScript and TypeScript.