Unless this is the wrong way to do it, someone please let us know. But I believe you change the track rule by using the option to toggle between ribbon and proxy selection, then select the track you need to change the rule, search for the rule you want, and apply it. And that should be all. Step 1: Step 2:
So that does change the track rule, but the 3rd rail remains the same from the previous track rule. There's no regenerate proxy selection in this instance, so what do I do?
You can regenerate proxy only in proxy selection mode. Are you confusing track rule with ribbon loft descriptor? Because I think the ribbon loft descriptor defines how the tracks look and the track rule is only presets for the track properties