i'd think there would be very little erosion in interstellar space, even over billions of years.
"Perhaps the records will never be intercepted. Perhaps no one in five billion years will ever come upon them.
Five billion years is a long time. In five billion years, all human beings will have become extinct or evolved into other beings, none of our artifacts will have survived on Earth, the continents will have become unrecognizably altered or destroyed, and the evolution of the Sun will have burned the Earth to a crisp or reduced it to a whirl of atoms.
Far from home, untouched by these remote events, the Voyagers, bearing the memories of a world that is no more, will fly on."
- Carl Sagan, Pale Blue Dot: A Vision of the Human Future in Space
All-in-all, it seems unlikely that a golden record would be all that useful.