Minha sugestão: Agências de siglas, agências do alfabeto; agências de sopa [macarrão / de massa] de letras / de letrinhas
. . .
"The alphabet agencies (also New Deal agencies [agências para reorganização / agências do novo pacto, novo acordo, nova ordem] were the U.S. Federal government agencies created as part of the New Deal of President Franklin D. Roosevelt. The earliest agencies were created to combat the Great Depression in the United States and were established during Roosevelt's first 100 days in office in 1933. Democrat Al Smith, who turned against Roosevelt, said his government was “submerged in a bowl of alphabet soup." en.wikipedia.org
♦ A far tougher fight may have to be waged against alphabet agencies that have become highly independent fiefdoms (áreas, departamentos, campos, negócios). time.com
♦ We can start by stripping EPA and other federal government alphabet agencies of powers to invoke unwarranted intrusions into our free markets, business and lives. forbes.com
♦ White House free-marketeers have lambasted such alphabet agencies as the CAB, ice and FPC for acting as guardians of the businesses they are supposed to regulate. time.com
♦ 14 of the New Deals Alphabet Agencies - Between 1933 and 1939 dozens of federal programs, often referred to as the Alphabet Agencies, were created as part of the New Deal. With FDR's focus on "relief, recovery and reform," the legacy of the New Deal is with us to this day. money.howstuffworks.com