Your term "interpretation" is difficult for me to put my arms around, but I will answer with what I have at my disposal and you can ask questions.

Many European cultures shared various supernatural beings. The Celtic world and the Scandinavian north, for example, had similar social supernatural owners of nature - fairies, elves, piskies, the hidden folk, etc., who were involved in similar legends and seemed similar in many ways. That said, each place often did perceive these entities as different: some would emphasis a particular nature such as small size or invisibility, and others would see them as more horrible and dangerous than elsewhere. So manifestations could be different.

There is also the problem caused by translations using native terms for foreign supernatural beings that seem vaguely related. Often these entities were not historically - genetically - related, but the use of a similar term in translated legends causes people to see the entities as similar when similarities do not exist.

Some supernatural beings - entities that have survived death come to mind - are nearly universal - but how they manifest can be very different, reflecting different traditions that probably have little to do with one another. Are the dead walking corpses or are they ethereal spirits? Do they bear ill will toward the living or are they helpful? The answers to these questions can help determine distinct cultural zones that do not necessarily influence one another.

In the same way, people have believed in spirits in the woods, in forest rivers, in the oceans, or helping with chores in the barn. Some of these appear to be related to one another while others are not. Grappling with the full spectrum of possibilities compounded with all the various "different European cultures" as you say can represent a lifelong journey, so this brief answer can do little but touch on the surface.

I hope this helps.