Please, don't scare me!
In 1848 the Habsburgs were forced to make a pact with their arch enemy the Tsarist (Czar) Russia, to put down the Hungarian revolution against the Austrian occupation. In 1956 the USSR (CCCP) just rolled in the tanks to put down the Hungarian anticommunist revolution. The "West" including USA promised help, but never fulfilled their promise. I talked to a USA retired officer who was there at the Austrian border waiting for the go order which never came.
So, Putin can dream about sphere of interest, but not about extra territory. The Carpathian Basin is Hungary.
I do not mean to scare. We know he thinks the entire USSR belongs to Russia, it would not be a huge stretch to add the old east bloc to that