Does Moral Science Think the System is Working?

I am struggling to understand an apparent contradiction in the Presidential Commission's report, Moral Science.

On page 42, we learn that

The current U.S. system provides substantial protections for the health, rights, and welfare of research subjects and, in general, serves to "protect people from harm or unethical treatment" when they volunteer to participate as subjects in scientific studies supported by the federal government.

But on page 55, the report concedes that

There remains a dearth of knowledge about the actual efficacy of human subjects protections. Given this, the Commission recommends that the federal government support an expanded operational research agenda to study the effectiveness of human subjects protections.

If there is a dearth of knowledge about the actual efficacy of human subjects protections, how could the Commission conclude that the current system serves to protect people from harm or unethical treatment?

And if there is a dearth of knowledge about the actual efficacy of human subjects protections, why does the Commission recommend that the federal government "require that all federal agencies conducting human subjects research adopt human subjects regulations that are consistent with the ethical requirements of the Common Rule"?