[apelapan]

My understanding of that type of "hävd", is that you need to have an official but incorrect deed of some sort, that remains uncontested by a true owner for 10 or 20 years.

Simply making uncontested use of the land is not enough.

I guess it is something that can happen quite easily in rural settings with very old property lines. Farmer 1 and 2 agree to some deal and a while later farmer 3 turns up and says "hey that's my land".