Actually i think the Sec is manipulating the crypto market since month/years, as specially garry ganssler is abusing his power. The SEC should protect investors, but actually they just deal more and more damage to us. So Is it possible to sue the SEC somehow? 
You will get the best legal advice if you consult a lawyer that is practicing in the United States of America. From the little I know it might be possible to sue the SEC in a US court and not in Germany. But I doubt if you can win this case because the SEC is claiming that it is protecting US citizens from loss of funds that might result due to the financial malpractice of Binance. Taking legal action against Binance and seeking a court injunction to freeze the assets of the company is within their legal scope of operation. So every court will rule that the government agency is performing its function except your legal team was able to prove otherwise. I will suggest you save your money and time instead of chasing shadows.