...and apperently Finnish word "Tonttu" is also a loan word "tomte" from Swedish...
...history is a messy thing... ¯\_(¬_¬)_/¯
Actually it's more likely the situation is a tiny bit more complex. The origin of the word in Swedish is "tomt", meaning a plot of land. A mythological creature looking after that lot of land was named "tomte". The bureaucratic/legal word "tomt" was borrowed into Finnish as "tontti" and then, following the Swedish example, it was turned into "tonttu", the creature taking care of the property.
