Well you need to know enough to know whether it's doing run time checks also.
And also whether it's generating less efficient code to satisfy the type safety requirement.
It isn't. Typescript is basically javascript with type annotations. There is a shorthand for class member initialisation and for defining enums, but that's basically it. There are no extra safety checks inserted. You get compile-time typechecking and nothing else.
But of course, a TypeScript program could be much slower than a different JavaScript program, as is probably happening in this case.
I agree with others that the difference in results between JavaScript and TypeScript makes the quality of this paper highly suspect.