For now, the mnemonic words is totally random which is hard for people to memorize.
You aren't supposed to memorize it.
So，how to store the seed?
Write it down on paper. Job done.
If you are desperate to store your seed phrase electronically, then encrypt it using a standard encryption method. Any time someone tries to come up with their own weird method such as this, they either make an error they haven't considered and so their whole system is so weak as to be easily attacked, or they make things so overly complicated that they can't actually recover their seed phrase and their coins at all.
In your system you need to store both your customized seed phrase and your customized word list file. Where are you planning to store both of these things? If you can't store them securely, then your system can be broken. If you can store them securely, then your system is unnecessary since you can just store a (optionally encrypted) seed phrase and passphrase instead.