This is available now, though it is surfaced in kind of a strange spot.
Rule order matters when a single event triggers multiple rules. As such, at the system level, it makes the most sense to have the order stored on the event itself. When you are adding an Event, there is a Rule Order field that you can modify. You can read more about the specifics here: https://docs.adobelaunch.com/launch-reference/managing-resources/rules#rule-ordering
In the future, we'd like to make a better way to get at the order field and make it easier to manipulate order in context of rules that share an event, but it is functional now.
