strange changeset

Why the area in this changeset spans across Europe if only one node was created and nothing was moved or removed?

Most likely an accident. They likely opened a map for editing in one place then opened up a second place not realising an edit now would result in a large changeset area. Maybe they had a cup of tea during the session and just forgot they had already opened the map for editing. If you open one tiny area for editing (but don’t edit there), then open another tiny area a thousand miles away, make an edit and upload, the changeset will be a thousand miles across.

This is just my opinion as I’ve actually inadvertently done the same thing myself. More than once.

In this case I don’t think it’s the user’s fault - I’ve seen similar things from “Go Map!!” changesets in the past. I don’t have a link to hand, but from memory the developers are both helpful and friendly, so perhaps you could mention it to them.