I've never seen a so evil Dumbledore and a Snape so fond of teaching Harry! Very nice.
But as to online translators.... God Forbid! The correct translations would be: - Sono a casa, nonna. (no need for the capital N not the article "la") - Ho dei voti perfetti, Sig. Snape. (marchi being the old German currency or marks on the skin and such)
Also: the correct spelling for grandma's name would be Sofia (if you were thinking about Sophia Loren, she changed from Sofia to be more 'international') and Danato does not exist... maybe you meant Donato? :)
I didn't mean to be an insufferable know-it-all by pointing out these little errors, it's just that I thought the corrections might come in handy if you plan on re-posting this fic somewhere else... and also, i'm in love with my own language and couldn't just sit and watch now, could I? :)