Danes and Swedes do not always understand each other's languages as well as the series may have you believe. But the creators decided to ignore this fact for the sake of a fluent dialogue. Also when people enunciate their respective languages as well as television actors do, people in the Malmö/Copenhagen region usually do understand each other.
Series creator Hans Rosenfeldt never overtly referred to Saga's social awkwardness as a result of her being on the autism spectrum to the cast, including Sofia Helin, during pre-production. He did explain to Ms. Helin the particular behavioural traits he would like to see manifested in Saga, but "feared any labels bestowed on Saga's odd-behaviour would prevent the actors from relating to the character in an individual and authentic manner."
"I did not want them to all rush off and learn a "textbook" approach to Asperger's syndrome or autism from the same source material".
By not giving the cast and crew a label or category to understand Saga's odd-behaviour, "I hoped that each individual cast and crew member would have a more personal reaction to Saga's character traits and research accordingly".
Throughout the series, Saga is often seen carrying a round container from which she obtains something that she then places between her gum and cheek. This is a pouch of Swedish Snus, a tobacco product that many Swedes use as an alternative to cigarettes.