Can Parallax Wave track a card moved by with Void Attendant?
As you know, the general rule is that an object that changes zones becomes an entirely new object (400.7). Then there are a bunch of exceptions to that rule which each allow an object to be tracked across one zone change - these exceptions are 400.7a-i as well as e.g. 406.6, which is the rule that allows linked abilities like Parallax Wave's to work. However, none of these exceptions will track an object across a second zone change, so Void Attendant will break Parallax Wave's tracking.

Intuitively, nothing is supposed to track an object across an unexpected zone change, but many effects legitimately need to track something across one expected zone change - e.g. it would be silly if a flicker effect wasn't allowed to find the creature it just temporarily exiled. Thus, the exceptions mostly boil down to "If an effect expects an object's zone to change, then it can track the object across the expected zone change." The public zone exception you mention (400.7h) is indeed somewhat anomalous because it can occasionally cause an effect that was trying to track one expected zone change to instead track one unexpected change. For example, in this scenario, Banishing Light attempted to move a commander to exile and instead the commander moved to the command zone. However according to the accepted answer, Banishing Light is trying to track the commander and did ultimately move it to some public zone, so 400.7h allows it to still find the commander even though the one zone change to a public zone wasn't the expected zone change. Note however that even in this unusual edge case, all tracking is still limited to one zone change.