This card has the same problem as Snoww, but is not as hated due to Snoww being the first and this card not being as useful as Snoww.
But anyway, the PSCT should have been like this:
If this card is discarded to the Graveyard by a card effect: Special Summon this card from the Graveyard; then if this card was discarded from your hand to your Graveyard by an opponent's card effect: Target 1 Fiend-Type monster on the field (if any); that target gains 500 ATK.
No it shouldn't. Targeting doesn't work that way. That would actively change how the card works.
The way they worded it is correct. And personally, I've never been confused by it. (And I don't see how people are, the texts of the two provide enough context to realize what's going on.)
Special Summoning it before choosing a target goes completely against how targeting works. (You choose the targets BEFORE the effect resolves. If this isn't the case, the card cannot target.) Them being two seperate effects, occupying seperate chain links, would also change how the card works. There was no way other than what they did to convey how this card works.
IMO, making them two separate effects that shares similar activation condition is the best way to do it. It only changes the card a bit (such a small change it doesn't really matter), but will convey the effect more clearly.
If this card is discarded to the Graveyard by a card effect: Special Summon this card from the Graveyard.
If this card is discarded from your hand to your Graveyard by an opponent's card effect: Target 1 Fiend-Type monster on the field (if any); that target gains 500 ATK.