They apparently aren't just raking in the kronor from TSR. I did a little digging, and have found another Swedish company called HemsidaDirekt (Homepage Direct) run by the TSR crew. This is probably public knowledge and I am out of the loop, but I found that this site lists their staff roster (I've translated to the side):

Jan Isaksson - VD (CEO)
Thomas Isaksson - Art Director
Johan Isaksson - Systemansvarig (Systems Operator)

And this company's address is listed as :

HemsidaDirekt (Homepage Direct)
Generatorhallen, Kungsgatan 3 (The Generator Hall, 3 King's street)
826 30 Söderhamn

...which is the same address as Ibibi AB, or TSR. So, I would assume the family operates quite a few money makers.

Edited to remove names not already stated in this thread

Though Jan and Johan have different pet-form names (Jannik/Janne), they are both modern-standard derivatives of the name Johannes.

The surname confusion is most definately translational, as Isak(sson) is the Swedish standard spelling of the Anglicised Isaac(son).