You'd think I'd have played with enough Chain Throws with that pre-errata Adon in my time to know the answer to this one, but I just want to double-check...

If I have a keyworded attack I enhance with Nursing a Grudge, and the attack does damage and is somehow discarded from the card pool immediately after doing damage (Tira's Gloomy E, Shattered Persona, etc), I can 'time' the abilities so that I can ****** the same attack back in to my hand, correct? Due to players being able to determine ability timing on 'simultaneous' activations they control?

always with the difficult questions Dave

If you set up two continuous abilities on your turn that would resolve at the same trigger, you choose the order. For example, Chain Throw in your mentioned Adon with Nursing a Grudge. Adon sets a floating ability, Nursing a Grudge sets another. They would both resolve if your attack deals damage. You choose the order of how they resolve, meaning you CAN get another Chain Throw, then discard the one in the card pool; however if you discard Chain Throw first, the game state won't remember its keyword to resolve Nursing a Grudge, so you would NOT be able to add the same attack back to your hand.

That's how I look at it.

I base this off of a ruling on the card "Arm's Length", which you should look up, where when you enhance with Arm's Length then block (it goes back to your hand), when Drifter goes to respond there are no blocks on the card pool anymore, so Drifter can't check for resources. In this case Nursing a Grudge wouldn't be able to check for keywords.

Correct, the game won't remember which keywords to match.