Celebrity hosts, major producers and a formula borrowed from the cult “Eurovision Song Contest” apparently hasn’t been enough to bring one of Europe’s most loved TV spectacles to the US. The US spin-off of the Eurovision has been suffering from poor ratings, and only about 1.5 million watched the last of five preliminary rounds on NBC in mid-April, down from around 3 million people watching the start of the contest. At the same time, ABC’s competitor “American Idol”, was watched by almost four times as many people, with about 5.6 million viewers. Ahead of its grand finale on May 9, the “Americ…