They knew about the problems (and the lack of solutions). Making it out of aluminum was a statement of the wealth of the nation - very much in the same way that the cap of the Washington Monument being made out of aluminum was.
Battleship New Jersey's First Hull Leak (not aluminum, same problems - made a decade before the SS United States) - https://youtu.be/DtNVAz_moAk
Battleship New Jersey's First Hull Leak (not aluminum, same problems - made a decade before the SS United States) - https://youtu.be/DtNVAz_moAk