East European teams by group:
A: Hungary 3rd
B: Croatia 3rd
C: Slovania 3rd, Serbia 4th
D: Poland 4th
Group E has three East European teams, and so at least one will make it to the next round. Group F has two East European teams and maybe one will make it. However, this has been a bad tournament for teams from Eastern Europe. I didn’t see anything inspiring coming from that part of the continent.
East Euro countries have little in common in terms of football heritage. They have their ups and downs independent from each other.
Slovakia, Ukraine and Romania are solid sides that could give problems to anyone on their day. Slovenia is having its best team ever. Hungary is still FAR better than it used to be in the 1990s and the 2000s. Albania is also better than ever.
It's only Croatia, Serbia and Poland that are underperforming, each for their own very specific reasons that are unrelated to each other. And of course Bulgaria which can't even qualify.
But overall I'd say most East Euro teams are better than they used to be 20 years ago.