If TypeScript has the integration testing framework in place to verify that the compiler actually works (and it should) - then, presumably, you should be able to swap in a Chinese Room black-box and - at least - know that it works.

You do have to be worried that it's possibly installing trojan horses on your computer while compiling code, or any other number of unwanted side effects.

But you can and should be able to have integration testing in place to know that a compiler - at a minimum - actually works.