Yeah, that seems very plausible. When I looked up the etymology of "skratte" in the most ~official~ lexicon Sweden has (Svenska Akademins ordbok) it said that since the 1930s the word has mainly been in use in northern Sweden, Swedish speakers in Finland and in Estonia. Which makes it quite the challenge to pinpoint where "canonically" the Andersons are supposed to be from, because they could have emigrated waaaay back, what with "skratte" as a Swedish word having been around since at least 1555. They could be from northern Sweden (say, around Kiruna) and have moved fairly recently or they could be from anywhere in Sweden and moved generations ago.

We've got so few words to go off in canon that their accents don't help much, but what I heard from them sounded very "contemporary generic Swedish" with no clear dialect markers. So I think, with how things stand, we fans can just claim whatever part of Sweden we want is correct and go with that 😁

I'm definitely tempted to write a "5 times Saga tried to learn Swedish + 1 time she actually got the hang of it" fic.......Just got to get through my gazillion other WIPs first 😅