You asked

"Second, of course, the hideous term: "enhanced interrogation techniques.’ I’m not sure where exactly this came from…"

Well, "enhanced interrogation techniques" is a fairly decent English translation of the Gestapo euphemism "verschaerfte Vernehmung" which was the code word for torture in the Third Reich. Look it up.

The dictionary confirms it. So Dean Barnett is picking up his terms from the Gestapo. Way to go, Dean.