dougpgc (paraphrased)
I asked him if a feruchemist were to visit Earth and tap Duralumin, could they do something as involved as talk local sports with someone?
Brandon Sanderson (paraphrased)
No -- when you trick your spirit into thinking it's from where you're currently tapping, it's not a full transformation, like Sel-ish magic making a copy.. It doesn't just fill your head with things from the place you're visiting.