This is extremely risky because it is really hard to know what seems obscure and what is actually obscure and humans are pretty bad at evaluating these probabilities with incomprehensibly large numbers. There are tons of famous lines in books that when used as seed phrases are instantly swept and with AI tools, it will become easier to find those sorts of things. There's a website that had examples of this.

Now, one thing that would have less of a risk of catastrophic loss is a one-time-pad. You can take a seed, and then use this memorable scheme to generate your pad, and then your padded key can combine with information you can find anywhere to unpad, but it becomes vastly more improbable that a bot would combine your padded words with arbitrary, obscure data.

From a bot's perspective, trying to unpad your padded words (which it might not find in first place) is strictly lower ROI because only your seed might be found, whereas searching obscure info directly, anyone's seed could be found who uses a scheme like yours.

Check this out to learn about how OTP works for seeds. https://pypi.org/project/seed-otp/