Tanks everyone for the answers!
Special thanks for your answer, I was able to solve the problem and wrote a script. It's very simple (I'm not a programmer), but works, in 20-30 minutes it generates all combinations of two words (about 1000) with which the seed phrase is valid (created in electrum v4, segwit type)

Hello! Please sorry for my english.

When I create a new wallet in Electrum v4 and choose to create a new seed (type segwit), the program generates 12 words.

I spent several hours trying to find a convenient phrase for me. Finally I got almost good seed. No, it's not simple, just contains words that it’s easier to remember only for me. But now I want to replace just a few words (for example 1 and 3) with others from the built-in dictionary to make it better for remember.

Of course I can't do this so easy because the checksum is violated, If I understood correctly, the last word is control? So I agree to replace it too.

It’s hard for me to understand the Electrum seed checksum calculation algorithm. Can I choose instead of this two word any from built-in dictionary and then somehow find out the correct last word? If not, perhaps possible to get a list of different words with control word so that I can choose?

I tried to choose randomly words (№ 1, № 3 and last) manually in the hope that button "Next" will become active, but in half an hour not a single successful attempt.

I think only a script can solve this task, who has any ideas? The closest I found is https://github.com/gurnec/btcrecover but as I understand it, it's suitable only for older versions of the Electrum (v1, v2) and not works with Electrum v3, v4 seed type