it doesn't have a animation going back to it's default position, instead it snaps back in an unpolished way further
This is not true at all. If the turret looks too far left or right toward its adjacent sides, it will reset to default position once enemies go out of its sight. You can test it yourself... And this had to have been manually coded for the turret to function like this.
It's like arguing about the function of music, I say it's function is to energise you while you claim it's function is too relax.
This is not the argument at all... We are arguing the reliability of the turret and whether its function was meant to be reliable. In other words, all I'm arguing is that it's not necessary for the turret to directly shoot at the players - that all it matters in terms of information is the brief window when the turrets gets alerted/triggered it will look toward the enemy's direction, such as Cypher ult - while you are arguing it is necessary for the turret to shoot at the enemies. The burden of proof/evidence is stricter for you than it is for me. And it is not difficult to provide evidence for my case either: all I have to point out is how the turrets are, in fact, dodgeable; that if its intention were to reliably shoot directly at its enemies, then the developers could have made the turret shoot an undodgeable beam of light, yet they didn't. A more appropriate analogy would be as if you argued music must be at a certain volume range for it to be qualified as music, while I'm arguing that music can be qualified at any volume so long as sound is produced. It's not an either/or case then since my perspective also allows your view within mine.
you still haven't given me a simple definition that includes one but not the other
I've provided the definition? Let me restate it: For a bug worthy of replay, there should be no room for interpretation of the item's intended functionality, while in other cases, there are room for interpretation.