I am not a native English speaker but.. I cannot help myself and I know it is not connected to norwegian but english.. still I am quite sure that the correct translation should be in the present perfect. it is not the first time now.. I had to write it finally (please correct me if I am wrong and sorry for a comment which is not fully connected to Norwegian)
That's fine if it's something that happens regularly - so every year. Present continuous though is about a temporary situation right now, but then you wouldn't use "living". The only way of translating it into grammatically correct English is to say "they have been living there for a while". It's still present tense, but links the situation "now" to the past, which the word "while" implies.