I don't understand how Staal can be misspelled so often.
Stall
Stahl
Stal
5 letters. How can you mess that up?
And as you pointed out the "sson" names in Swedish are quite simple, Take the name Karlsson for ex. It means son of Karl = Karl's son, then just merge it. Or Ander's son etc, etc...
Most Finnish names are tough, generally speaking.