Perhaps it's more fitting not to erase these names, but rather append swastikas to them, guiding readers towards a plaque that elucidates their heinous crimes as Nazis. In this way, the monument will persist as an enlightening reminder of who exactly the "victims of communism" truly are.
I may make multiple signs. One of them is definitely going to be the old wikipedia notice of "This list is incomplete, you can help by expanding it."