It's awesome! I like most suggestions, it feels a bit like
https://wiby.me/surprise but generally less weird.
I've often wanted to have a go at making my own search engine, and I think I would penalize any form of advertising (especially big ad networks, referral links) or tracking (Google Analytics, etc.) as these can create (or reveal) perverse incentives. This would likely get rid of most of the "SEO spam" that we see nowadays. Reading the about page[1], this seems like what you are doing here, but I can't really tell as it's light on details.
Q: would this be able to handle foreign-language sites? I don't yet have a blog/personal website, but if I did, I guess it would be mixed-language. Should I submit some of my friends' blogs, even though they might not be entirely (or at all) written in English?
A relatively new sort of search-engine junk, especially visible in non-English results from big search engines is also auto-generated (or probably machine-translated) websites, full of nonsensical content. They might be translated from genuine sites in other languages, I'm not sure. It would seem hard to fend these off, but luckily, fighting perverse incentives such as advertisement revenue probably gets rid of them too.
I also wondered if this was curated list, and if the list was available somewhere, but it seems it's just a good old spider, and I guess that exposing too much info about the metrics might enable some to game the system? Not that marginalia is big enough to make it an attractive target, of course!
[1]: https://memex.marginalia.nu/projects/edge/about.gmi