I do not understand "When I need to rename my curves to [an] existing name, it require[s] me to delete all curves and re-add with “Add Variable Curve → Available Names…”
You can type in new names right here as long as you are not repeating the same name of a track already there (For example, you could change this “5” to a “4” but not to a “1” because track “1” already exists):
