Verified answer

You're completely correct. I really hate to address other answers because I feel bad whenever someone says I'm wrong, but I feel compelled to do so, so that you don't change your perfectly good sentence. Glottonyms (the names of languages) are never capitalized in Italic languages (including Spanish) unless they start a sentence. Therefor, the "i" in inglés should remain lowercase.

Your translation of "seven deadly sins" is also correct. In Spanish (and most Italic languages, for that matter) their name literally translates as the "seven capital sins"-- so "siete pecados capitales" is correct. The name would not be literally translated.

It's correct.

There are no mistakes at all.