Philosophy behind pointing out missed triggers
It seems like everytime I think I understand missed triggers, something else causes me doubt. I'm likely overthinking, but trying to find solutions has only raised more questions. As such, I'd like to ask about a few examples.
Most players familiar with competitive Magic are aware that some triggers your opponents control don't have to be pointed out. These are usually beneficial to your opponent.
E.g. Nate doesn't have to point out Ann's prowess/exalted triggers. Straight out of IPG 2.1, if Ann attacks with alone with a Knight of Infamy and says “Take two”, Nate can take 2 damage with neither player receiving a penalty.
Q1. Prowess and Exalted have invisible effects on the game state. Does Heroic work the same way despite having a visible effect? I.e. does Nate have to remind Ann to put a counter on the Heroic creature if Ann forgets? I'm almost certain the answer is no but I'd like confirmation.
From IPG 4.8 (Cheating), example D suggests that Nate is cheating if he notices that Ann only resolved half of Sword of Feast and Famine's trigger.
Q2a) Does it matter which half was resolved? Or is the problem here that a trigger cannot be allowed to only resolve halfway?
Q2b) If the Sword's trigger was split into two separate ones, would this still be considered Cheating?
Q2c) If Ann failed to acknowledge her Sword trigger at all, does Nate have to remind her?
Q2d) If the answer to 2c is Yes, does this apply to every Sword? E.g. for Light and Shadow, shouldn't Ann be able to miss her lifegain trigger and have it assumed she chose not to return a creature to her hand? If the answer to 2c is No, disregard this.