It's just 2048 english words and the dictionary is known!
It doesn't matter. There are 2
128 possible valid 12 word seed phrases from the standard wordlist of 2048 words. You have failed to grasp how big a number that is. Re-read the numbers I have explained above. There will never be a collision between any reused seed phrases in the entire future of the human race. Feel free to start randomly generating seed phrases and checking them for balance if you want, but I guarantee that you will find absolutely nothing.
This is also the reason why we found out whose wallets are of Satoshi Nakamoto's ownership, because he signs a message on his wallets.
No he didn't, and we don't know for sure which addresses belong(ed) to Satoshi.