It gone because if mixing wallet mnemonic seed and many random words which are not wallet mnemonic seed words.
I'm not sure if I understand you correctly, but nope, OP said that it's all words from mnemonic wordlist. He basically failed to document his own obfuscation or correct pattern how to find his mnemonic wallet recovery words in his grid of words.
Maybe his recovery words are at prime number positions in his extended list of words or something similar, like jumping like a chess bishop on a grid of words. Possibilities are vast and I always wonder why people invent something but fail to document it. Because one thing is for sure: you will forget whatever you invented when you don't use or repeat it regularly.
Loss due to complexity / not being able to restore from backup
Complex your wallet back up will not make your back up safer but more risk of failure in recovery later.
Not much to add to this. Add complexity and/or obscurity and fail to document it for you or your heirs and you have a recipe for desaster and loss.
Whatever you do, you should verify if you can successfully recover your wallet(s). If you have your non-standard procedure(s) only in your head, it's almost guaranteed you will forget something and shoot yourself in your foot. Don't do this, apply KISS principles!
I have about 30-50 seedphrase words here
What an odd way to describe how many words you have.
Indeed, I would think it should be possible to count the words and tell the exact number. Not that it would make much of a difference. Without any clues, you can't really brute-force this. You don't have the time and/or the energy to exhaust the search space.