I love this. Sometimes Swedish words are hard to translate because they are compound words or because they are some weird metaphor. For example, the Swedish "Smultronställe" is quite literally, "Raspberry place", and refers to a favourite place a person likes to go to. There's also "realisationsvinstbeskattning" which means "capital gains tax" but just squashed together (we do that with words that go together). If we take this to the extreme we can create words like "spårvagnsaktiebolagsskensmutsskjutarefackföreningspersonalbeklädnadsmagasinsförrådsförvaltarens" which means “belonging to the manager of the depot for the supply of uniforms to the personnel of the track cleaners’ union of the tramway company”, but isn't a real word.
Some other cultural notes you might want to update:
I would change Sisu. It is not Swedish, it's Finnish, and it's so Finnish that a person who doesn't exhibit this trait is often not considered a true Finn.
"Lagom är bäst" is not a word, it's a phrase that is not even used much and is already covered by the word "lagom".
Självklart literally refers to something self-evident, it's very nature is "clear" as in clear ice for example and requires nothing outside of itself to be understood.
"Kompisar på nätet" is not a thing, but "Nätkompis" is.
"Mellanmjölk" is described as semi-skimmed (literally middle-milk), which comes from our phrases "light milk" (0.5% fat), "middle milk" (1.5% fat) and "standard milk" (3% fat). You could also add those if you want, they're called "lättmjölk", "mellanmjölk" and "standardmjölk" and is simply a three-tier system for easy colloquial reference. But what makes this mellanmjölk word interesting is that it can also be used to refer to something that is bland, boring or unremarkable. For example, in the Swedish Idol, a jury member said they thought an audition would be a "Mellanmjölksvariant" (a boring audition).
There is a sound used in Northern Sweden that is literally a short inhale of air, which is used to express agreement. Southern Swedes are not always able to make the sound convincingly. It's not quite the same meaning as "yes", as it just lubricates the conversation and shows you're listening. It can also have a stoic and unbothered character to it.
https://sv.wikipedia.org/wiki/Inandnings-jo