Hmmm, leaving aside the そんなこと for a second, you've ignored the negative at the end of the Japanese sentence, and so even if you had the other parts correct you would be making a fatal mistake unless you deal with the negative.
そんなこと = is literally "that thing", or "that kind of thing".
Typically it will be used to indicate some small, petty, or seemingly insignificant thing, and you can tell this from the context. In this case, it has the qualifier など at the end of it, which removes all doubt. So therefore the そんなことなど might be translated as "such insignificant things" or "such trifling matters".
And, もっとも is different from もっともっと!
Oh, and don't fret the double は. Its just part of the phrase that's imbedded in the sentence