We have similar laws: it just means that when you find something, it's not automatically yours. I think there's a 1 year time limit here for the owner to show up.
In Spain you should give it to the Mayor of the city where you found the paper wallet and, after two years, if nobody claims it, it would be returned to you so it would be yours. In the case you don't do it, it would suppose a crime of "misappropriation". (This figure is 133 years old 
)
....like I said, too many laws, too much restriction of freedom, too much government involvement. Somehow when someone loses something and another person finds it, the government has laws in place that mandate their meddling (for lack of a better word). I'm not an anarchist by any means, but if we're talking about someone finding something like a seed phrase where it's pretty damn hard to prove ownership of and puts the finder at risk of some potentially very unwanted publicity, I say the law conflicts with what is right.)Just my opinion, though. Hey OP, perhaps keep us updated if you pursue the find-the-rightful-owner route? I'd understand if you went immediately silent, however. *that's what I'd do*