Ideally Launch would include the same functionality to mimic the _satellite.dtmRuleStackArray functionality that is in DTM. Doing so provides a great audit mechanism, as well as a way to perform a gap analysis for rules that are not in use.
I think that at some point in the past, I wrote a monkey patch on top of _satellite.notify that would create and maintain _satellite.dtmRuleStackArray... I'm pretty sure that what you're looking at is a custom artifact and is not part of vanilla DTM.
I found that since _satellite.notify is called regardless when any rule is fired, it was a convenient intercept to grab the rule name and apply it to an array.
Anyway, the good news is that you don't need to rely on a hack to get the rule name anymore.
You can grab it like so:
//This is a rule condition (type = core : custom code)"
_satellite.logger.info("Rule Name Is : ",event.$rule.name);
Also, you can just use data element syntax in the UI if you prefer... %event.$rule.name%
The _bad?_ news is that if you wanted to do this automagically on every rule (from within the property), I think you'd be out of luck.
The _good_ news is that there is now a set of monitoring hooks for Launch that you could use to good effect with a little bit of coding. See Aaron Hardy's post on this topic. https://medium.com/launch-by-adobe/launch-library-monitoring-hooks-8495dd91b57