The statistician doesn’t go so far as to make this claim. She merely claims that the studies are flawed, without taking a position on whether procedure X actually does cause disorder Y.

This is a good paraphrase of the conclusion. “Unsound” and “flawed” both get at the same point: the studies are unreliable.

There’s no recommendation in this argument.

Also, the statistician doesn’t suggest that studies of procedure X and disorder Y aren’t extensive enough in general. She only says that these two particular studies aren’t extensive enough.

This is contradicted by the statistician’s claim at the top of the stimulus: the studies found no causal link. Then, she constructs an argument to discredit the reliability of those studies.

We can’t assume that these studies were conducted by “many medical experts.”

Also, the statistician only considers these two studies—she doesn’t suggest what has or hasn’t been established outside those studies.