But they're not. TWW tells us what happens to the ToC...
TWW tells us what happens to the Triforce of Courage when Link goes to Termina. When he goes back in time, he clearly takes it with him. It's seen glowing in his hand in the child-timeline ending of Ocarina.
False. Read the translations from the Japanese version, and the Hylian intro text - both refer to Link leaving Hyrule by going through time.
I just quoted the Japanese version that clarified he left Hyrule
. He certainly didn't leave Hyrule when he went back in time. The only time the Hero of Time leaves Hyrule is 1) when he's in the Sacred Realm and 2) when he's in Termina.
The Triforce mark on Link's hand has been established many times to not require actual possession. The same thing happens at the end of TWW, after the Triforce pieces are separated from their owners. It's NOT on his hand before Link goes to Termina in MM.
Granted that the mark isn't necessarily indicative of possession. However, what other reason would the developers take the time to apply it to his hand if they weren't trying to indicate possession? Furthermore, it works the other way too. Link had the Triforce of Courage for most of Ocarina of time without the mark appearing there. Just because it isn't visible doesn't mean it is not inside him.
What on earth do you think you're seeing? Link appears back in the Temple of Time, the Master Sword is ALREADY there, because he went back to before drawing it - that was the entire point of the ending, he goes back to that time when the Master Sword is still in the pedestal so that none of those events happen.
The point at which Link arrived in the past is conjecture; the Master Sword, as best I can tell, is pedestal because Link put it there to seal the timelines off from each other. Link has it
in his scabbard when Future Zelda sends him back in time, so unless his Adult Body and the Sword stay in the future, the sword goes back with him. I think it's safe to say that what Zelda does to Link at the end is rather different than Link's spiritual time travel through most of the game, since it creates an alternate time line rather than changing the existing one.
If he'd brought back the MS with him, there would be two Master Swords.
Not if he arrived after the sword was sealed in the Sacred Realm for seven years.