This is a land swap. In none of the other examples you give would there be any possibility of a land swap.
But sure, if two countries agree to modify their common border, why shouldn't they be able to do so?
It is also a people swap.
In 2001 there was fighting to the north of Skopje.
My wife watched on many evenings from an apartment block balcony Mi-24s strafing villages 10km to the north.
I think that the people who were fighting thought that there was a possibility of the border being moved.
Countries are free to modify their common border unless there is some treaty restricting the change.
The problem is the precedent that it sets.
It gives hope that other ethnic groups can get the border changed where you think there is no possibility.
And where there is hope but no possibility there is often war.
Why should the EU be consulted at all? Member states are still sovereign nations and should be allowed to make such decisions without "approval" from Brussels.
Well the EU is hosting talks between Serbia and Kosovo. So if Serbia and Kosovo put up the border for discussion by definition they are asking for comment from the EU. The EU has not rejected the idea but is cautious.
https://www.euractiv.com/section/enlargement/news/eu-ministers-wary-of-kosovo-serbia-border-changes/
The EU has been involved in talks for a few years. See Quote and link Wiki article on 2013 Brussels Agreement.
15. An implementation committee will be established by the two sides, with the facilitation of the EU. .
https://en.wikipedia.org/wiki/Brussels_Agreement_(2013)
Or the EU can stop overstepping their authority.
Serbia and Kosovo are not in the EU but are in talks to join it. As such the EU has been given an interest in their counties by Kosovo and Serbia.
It is a threat. You just essentially said "abide by the EU's opinion, or they will make life uncomfortable for you." That's a threat. And a threat the EU has shown it will make good on given their proposals for sanctions against rebellious members like Poland.
So if some Caribbean Island raised the possibility of the Chinese building a small naval base to help boost the economy the US would express no opinion. What if the island also wanted to become the 51st State.
The US has expressed a positive opinion over the possible Kosovo and Serbia border swap, did they overstep their authority. If the US feels it can express a positive view for one outcome of a negotiation it is by implication giving itself the possibility of also disagreeing with that outcome.
Could we just have all our lands back please
?
No.
The existence of both Serbia and Kosovo as independent states is itself precedent for drawing and redrawing borders along ethnic lines, this is just fine-tuning. Leaving it to diplomats rather than warlords can't be our least-bad option.
I would agree with you for the most part I just do not think it is a good idea to start chopping up countries again in Europe again along ethnic lines.