It's possible that this "phrase hash" method was used for a different case - like another, unrelated and possibly unreleased algorithm. And then it was confused for the one used for those curves.

There is one that Claude couldn't find perhaps that is from the phrase.

But I do agree, it is unusual actually that the code was lost.

It is also unusual that they didn't include how they derived the seed, and weren't forced to pick a randomly generated one.

I guess these are all things that would happen today but this was not so long ago to my mind so it is a surprise it didn't happen!

One possibility is that they created multiple seeds, and misremembered which one they eventually went with. Although, it's weird no one ever said "or it might have been a timestamp".