As I posted in Rocco linked to Michael thread:
Godfather movies are not documentaries not factual They are for entertainment Technicalities not intended, in fictional stories
It is nice to know, fun to flesh out but not critical for the audience to be knowledgeable about the legal details, to enjoy the movies

Once He chose to reveal Pentangeli the perjury trap was no longer a trap because Corleones could identify and counter that person

Again nobody could uncover Michael's hidden interests not even the FBI Nobody could nail him because his web of fronting was like fort Knox