Your argument is coming across as vaguely racist and appears to be based on nothing but the divisions imposed between the second and first world.
All 4 of them (if you count Poland, counting Finland or Sweden would be even harder). Here is a Latvian joke about Estonia: "no sex or future in Estonia". I have been in pretty much any European country, minus Portugal. No idea where the racism idea comes from, though.
You just showed how stupid of a construct the whole 'western/eastern' nonsense is
So here we would consider the balkans to be eastern.
Is there a hard criteria at all?
And even in "the west" (by which I would mean the top ~40 countries by HDI), "the west" is a poorly-defined term.
Edit: turns out Wikipedia has an article about "Western world", which makes it quite clear that the term is vague. Apparently the original meaning was "Western Christendom", so it's a religious thing. TIL.
> USA-centric concepts
It means the same in other languages. And English is, AFAIK, also spoken outside the USA. If I'd call anything to the east of the Poland "Mongolia" or "Eastern Asia", I think people wouldn't understand me or think I was being obtuse.
(In a similar way, the Europe / Asia / Africa divide is fundamentally a Mediterranean concept. The farther away from the Mediterranean you go, the less sense it will make.)