With any programmable art, it's very important to get the artist to set the parameters of future modifications. In San Jose when we did a number a lighting projects, and one with a digital sign, we asked the artists specifically what they would allow. For instance, one artwork very near the "Shark Tank" where the hockey team plays, the artist allows the piece to be switched to the team color on game nights, but beyond that he would need to be consulted.

Changing programming is tantamount to repainting a mural and seems to me an artist could make a legal case. Better to get the permissions at the front, but if not, you should definitely consult the artist.