The issue is that they aren't confederate statues. They are daughters of the confederacy statues and were deliberately put up to make people not feel welcome and in such a way to make people believe it was about the confederacy and not about just kicking black people out. A statue is only valuable as a statue when it's clear what the idea behind it is. Details on a statue only serve to enhance your knowledge of that ideal that is being represented not to completely change direction. We have the Statue of Liberty that very easily stands for welcoming immigrants to a land of freedom and prosperity. However she also has details that explain how not only are we about these things, we are about these things for literally anyone including the tired, poor etc.

It wouldn't make sense to have the Statue of liberty up which represents freedom and prosperity and then put a plaque on the bottom to explain "surprise! it's actually a dictatorship with slave labor!" (obviously the US isn't in this situation). In the same vein adding just some words to try to reverse the large symbolism won't be powerful enough and just erecting a statue next to it won't erase that symbolism it'll only state that these 2 ideals are considered equal in society.