I think what you may be missing is the fact that laws implementing treaties are subject to interpretation and further that the defense in a criminal case may raise issues of law that override the letter of a treaty.  E.g., just because a treaty says thou shalt not kill does not mean everyone charged with or investigated for killing will be convicted. There are defenses to the charge.

In the case of torture, the definition is not completely agreed upon. While you and I may call something torture, a government, i.e., the one in the USA, may not. While many have long held that waterboarding is torture, the US Government, during the Bush Administration, officially stated it was not and directed government employees to behave as if it were not.  Now, suppose the accused CIA employees were acting upon a similar instruction.  Unfortunately, the wording of the treaty (particularly para 3), though it appears iron clad, potentially becomes full of holes when subjected to the law in local national jurisdictions.

  Please understand, I'm not saying the CIA employees will be able to escape justice using this defense. I am only providing my layman's interpretation of the possible legal defense set forth in the interviews referenced. I know almost nothing about the cases that are being investigated.

I can swear there ain't no heaven but I pray there ain't no hell. _ Blood Sweat & Tears