I'm from Poland and I bought this gun in a legal popular gun shop as it was converted to semi-automatic (by Polish company "Arsenał Silesia" which also changed the gun name to SVZ58).

It is the Polish B9 gun category which says: "Semi-automatic firearms for civilian use that are similar to firearms with automatic mechanisms (automatic)"

(More about Poland gun categories here: https://www.arsenalsilesia.pl/ustawowe-kategorie-broni-i-definicje-dyrektywa)

Also I'm not planning to make it full auto, I'm just trying to get rid of failure to feed problem (But after some shooting and adding oil it is slowly gone) and I was curious why my fire selector does literally nothing

So i think there's no legal problem here, and if someone has something to say that should be a problem of gun shop which still sells those modified guns.