Counter Galois Onion: Improved encryption for Tor circuit traffic (opens in new tab)

That is correct. But, (in general) encryption does not necessarily guarantees integrity of the data. In other words, a plaintext can be encrypted, the ciphertext given to another party, and they can tamper with the ciphertext in a way that produces predictable changes in the message obtained by decrypting the tampered ciphertext.

Sure, that happens.

But instead of just reporting it directly, we instead get this unsubstantive comment (“Cool! Great! Btw you spelled a word wrong.”). Essentially just noise, nothing that provokes curiosity or interesting discussion.

There are countermeasures you can take against timing attacks, pattern analysis, and other capabilities an attacker may have if they control many relays. If you're trying to exfiltrate military secrets to the Russians, you can probably do it, but you'll have to be extremely careful. Your behaviour is as important as the network you use to communicate over, if not more important.

There is no single state actor that has access to all data centers in the EU, though. For some countries, there's barely a state actor that can access all data centers within a single country.

There is no tool that will let you become immune against a theoretical hyper powerful super government that controls all data centers, just by clicking a button. There never will be.

You may be interested in Katzenpost and the research behind it: https://katzenpost.network/

Don’t things like Freenet do similar?

Except that every user is also a node, thereby mixing their personal traffic into a share of network traffic. Or so I understand it.