I'm not up very well on current terminology, but maybe I can give you some insight.
The original Mopar electronic ignition used a magnetic pickup. With that in mind, as the blade on the reluctor turned and approached the pickup, the magnet should sense the the approaching reluctor blade as it comes around (which I would call the rising edge). The magnetic pickup would also sense the reluctor as it passed (the falling edge). The distance between the magnetic pickup and the reluctor was a critical measurement in the early Mopar electronic ignitions. Were I betting, I would suspect the Mopar unit would fire the spark at the point at which the magnetic signal was probably within the predetermined range (as determined by the tolerances built into the magnetic pickup), which should have been close to straight up.

The thickness of the reluctor edge can't be more then a couple degrees either way (between the rise, the center, and the fall), I don't see how that could cause a no start unless your timing it at the very edge of function. The gap between the reluctor point and the magnetic pickup could probably be effected by the condition of the distributor bushings more then the leading or falling edge of the reluctor. Later versions of Mopar electronic ignition use a crankshaft pickup to eliminate the variables a distributor could cause. In short, your electronic signal could be fluctuating between cylinders or between dist revolutions. You have to keep in mind the Mopar electronic ignition was the 1st ever production electronic ignition system and compared to the old point system everyone else was using, was very far advanced. Automotive electronics have come a long way since 1972 when the 1st Mopar electronic ignition systems showed up on the option sheet. Gene