I have seen references to that sourcebook, and always thought it was some fan made material. So they made their own licensed stuff over there? Cool
Unfortunately, considering the language it would be not be much point of getting my hands on it. If it had been in Swedish... Oh, well.
Reading on wikipedia I can see that the
Baltic fleet at Leningrad has the task of securing the coast of Germany and Poland, and give amphibious capability to be able to attach Denmark and Germany.
So no reason to break out and engage in the battle of the Atlantic, thus southern Sweden or eastern Denmark would not be considered an immediate threat.
Denmark and Holland (and possible Belgium depending on if they stay in NATO or not) would be transit lands for US and Canadian troops and supplies. While denying access to those ports would be of interest, I don't think it would be done by an amphibious invasion of Denmark. Strategic bombing and later nukes would probably be the method of choice.
If the invasion of Norway would be halted in Lapland, then the rest of Norway would probably be quite untouched until the nukes starts to fly. If the invasion of Norway is successful, I would guess quite a few resistance group would have their bases on Swedish soil. The later could mean the same type of tension as the one between Colombia and Venezuela/Peru as FARC and other groups have used bases across the border.
But it can be worth to remember that one of the main objective to invade Norway during WWII was to secure the import of Swedish steel.
Apparently, there was some plans by the British to invade northern Sweden to deny Germany the option to import from Sweden. Those plans was scrapped. So a question is, how important would imports from Sweden be to Germany and Great Britain in the Twilight war?