What nonsense. That US Democratic Party politics often leans more right than many popular European parties on the left is not some modern post-Obama discovery, and was widely understood long before Obama's presidency. Literally read any political memoir or history by a left-leaning European politician who interacted with the US and Democratic party leadership prior to Obama and you will pick up a sense of this.
I can accept arguments Obama may have been treated with much more interest and excitement than perhaps he warranted in European media at that time, but I see little evidence this was because his politics were misunderstood - Obama's policy positions were generally easy to articulate. I think a simpler explanation might well lie in the obvious historic nature of the event; he was the first black man to hold the office, and the first Democratic president after two terms of Bush. These facts alone are "newsworthy" by the standards of modern media.
"leftist" is an absolutely terrible classification to use in any debate about politics, given its generally only ever used reductively and is almost devoid of any actual meaning.