I cant find any info about that proof that Tether is beeing backed by real U.S $.

Tether is a straight up scam as far i can see it, things will be more clear later this week.

They made the claim on their site and said it could be verified by looking at there audited accounts. That being said, even there accounts showed certain discrepancies (http://www.newsbtc.com/2017/03/21/tether-balance-sheet-unveils-large-discrepancy-usdt-usd-reserves/) and what's to say that the auditing wasn't fabricated either...