Whoa, wait a second. This is kind of pinpricking, but I just want to get it straight. I'm pretty sure Vin did not Snap at birth. As far as I'm aware, I thought it said somewhere that no one was really sure when Vin Snapped because her life had had so many traumatic points. The first traumatic event in Vin's life we know of is when her freako mom Spiked her and killed her sister.
Also, someone probably already said this, but Sazed did not "swap" cadmium and bendalloy with atium and malatium. Atium and malatium were mistakenly placed in the Allomantic table as they are not from Scadrial. That's why when you include those (lerasium included) in the list of Allomantic metals, you get 19, not 16. They were not supposed to be in the table in the first place.