if you look at the law, unemployment is listed first, inflation second.
We hear that a lot but here's the actual law and it doesn't say that; all it's got is stuff about what a 'good' economy is supposed have. So what the Federal Reserve says is that--
"...maximum employment could best be achieved by achieving price stability..."
"...the Committee could achieve its dual mandate by achieving the price stability objective..."
--and no matter what the 1978 law should have said and was meant to have said, the Fed's tools stay the same. They affect prices, and that's why the Fed admitted that the 1978 law did not affect:
"...the Committee’s view about how and the extent to which monetary policy is capable of increasing the level of output beyond achieving price stability."
I'm not sure what you are looking at, but here's the actual Federal Reserve Act as embodied in U.S. Code. USC_Title 12_Chapter 3_Subchapter I_§ 225a
USC ›12 USC § 225a - Maintenance of long run growth of monetary and credit aggregates
The Board of Governors of the Federal Reserve System and the Federal Open Market Committee shall maintain long run growth of the monetary and credit aggregates commensurate with the economy’s long run potential to increase production, so as to promote effectively the goals of maximum employment, stable prices, and moderate long-term interest rates.
Title 12 is "banks and banking" with Chapter 3 specifically the "Federal Reserve System". You're link was off in Title 15 Commerce and apparently deals with things the President is authorized to do, not the Federal Reserve.