The legal matrix is very complex I agree, but FHFA cannot be compared to the CFPB, yes they are similar in some way, but FHFAs HERA is the controlling statute and that does differ quite a lot, so when you say the “12 U.S.C. § 4512(b)(2) in legal-ese, never existed” it needs to be severed from HERA but without this provision the president blocks in another part of HERA judicial review per § 4617(f) and in again another part of HERA it says 12 U.S.C. § 4617(b)(2)(J)(ii) it can act in the best interest of the FHFA, this is unconstitutional per the separation of powers as the president thus now can act in its own best interest all allowed by congress who gave the president the power to self-deal, this again is a violation of the separation of powers and courts cannot make unconstitutional ruling as they must review HERA in Toto,(not as you say provision by provision and the violating provision must be stricken) so the FHFA looks to be void-ab-initio if congress doesn’t change the structure and give parties interested compensation for their wrongdoings
So to conclude the CFPB is an agency within the Federal Reserve System which has a Board of Governors, absent say the “for cause” provision the Federal Reserve System still had the authority, this differs from the FHFA as absent the “for cause” provision the president blocks Judicial review and as the FHFA survives by assessments the president thus makes assessments for his own best interest, so the structure is not legal nor can it become legal without congress
Hope this enlightens somewhat
