"Some Googling to find the actors ages finds that one is in a film presented at the Sundance festival called Copenhagen https://en.wikipedia.org/wiki/Copenhage
My curiosity was piqued as to whether it was going to be as daft as it sounded...
It wasn't on LoveFilm by Post, presumably because there isn't actually an English language release, despite it being (mostly) in English, so I got a German DVD of it, which of course has the original sound track. In fact someone has, tsk tsk, put the whole film on YouTube. Unfortunately this means that the bits where they speak Danish have on-screen German subtitles (it doesn't have subtitles for the film in English or German as far as I can see). Or rather for the first half the bits in Danish have on-screen German subtitles and then the obviously got bored and stopped. Possibly on the German sound-track they are just dubbed into German - the ones in the first half it's relevant to the plot that some of the conversation is in Danish and tiresome-frat-boy can't understand, the ones in the second half are just manic-pixie-dream-girl talking to her family so why not just have them dubbed into German, I suppose.
It was everything I expected and more. As with my comment about Deutschland-83 about them thinking 'well, we want to do a cold war plot that only works in 1983 and an AIDS plot that doesn't really make sense until 1987-8 but fuck it let's do it anyway', I think they must have thought 'well, we've got this idea about a 28 year old tiresome-frat-boy meeting a manic-pixie-dream-girl and finding out she's 14 but actually that would just look creepy so let's have a 19 year old actress who looks 19 and whose character acts like she's 19 - within the constraint that no-one really acts like manic-pixie-dream-girls though we have a barely-plausible 'oh well, she didn't know her real dad so helping irksome-frat-boy find his grand-dad resonates with her somehow so somehow she can drop everything and spend two or three days cycling round picturesque bits of Copenhagen and doing manic-pixie-dream-girl stuff' - and yet say she's 14 and then the irksome-frat-boy can be petulant for a bit when he finds this out and then after about half a scene go back to relating to her as though she's 19 which of course she is really.'
Also the plot is that it turns out that he granddad was a Nazi / Nazi collaborator. But, folks, for this to work he's going to be at least in his mid to late 80s and yet of course the confrontation scene wouldn't work if he goes to meet feeble old dude (not that all people in their late 80s are feeble) so let's have a healthy looking bloke who looks like he's in his early 70s.