Sorry, but I don't have the programming skills to comment on your project. I will check the responses of other members to see what they say. There are those who know these things. Maybe you talked about it in your thread, but I have to ask, why generate private keys if you can generate 12/24-word seeds? They are longer strings and difficult to write down. Therefore, the possibility to make a mistake is greater compared to a sequence of English words, for example.
Actually a private key is nothing more than a 256bit random sequence (e.g. 010110...1001)
The words that you refer to, derive from this 256bit number, if you add 8 bits more (checksum).
Therefore, it is quite simple to get the words, like you mention above.
However, I also generate a QR code, which is what I keep track of in a custom QR template. I took this idea from SeedSigner's QR template. It is basically empty and you fill it up with the information you see on the computer.