People around here don’t talk about Plainfield or Bueno any more. Occasionally, you hear it referred to as Poverty Flat, another old name, but not so much. La Sal used to be called Coyote. Names change over time.
Almost every geographic feature on the North American continent changed names as white settlers moved west. When was the last time you referred to the mountains outside of Flagstaff as Doko’o’osliid? For most, those mountains are now called the San Francisco Peaks.
Changing the name from Negro Bill Canyon to Grandstaff Canyon is going to be okay. An interpretive sign will be at the trailhead explaining the history. We are halfway there. The name of the campground adjacent to the canyon is called Grandstaff.
Names change, they always have and always will. It’s okay.