In the political sense, «Western Europe» is typically taken to be «NATO Europe», and «Eastern Europe» is «Warsaw Pact Europe». Which is different from a strict geographic definition.
You’d have to say which NATO. Czechia is in NATO and was in Warsaw pact.
If you said: Americans usually incorrectly think of Western Europe as those countries not partially or fully under control of the Soviet Union during the Cold War, then I’d agree with you.
