Hey there! You're right that documentation is a huge part of this program.
Curators and nominators both work from Medium's Quality Guidelines: https://help.medium.com/hc/en-us/articles/360006362473-Medium-s-Quality-Guidelines-How-curators-review-stories-for-Boost-and-Distribution
These guidelines are updated regularly, with our curator manager writing about the process: https://blog.medium.com/how-our-quality-guidelines-incentivize-your-best-writing-and-how-we-curate-those-stories-for-our-c1c7310e3950
In addition, I also share Medium's Curation Training manual with nominators: https://medium-teamspace.notion.site/Medium-Curation-Manual-How-to-Assess-Story-Quality-01277bfcb0d94894b80f4aa1be76ade9
That said, part of this shift to human curation is that, unlike writing for an algorithm, it's not formulaic. That's by design. We tried an algorithmic, formulaic approach to curation, and it did not work -- the story quality on the site was low, and membership dropped. I understand that human curation can be frustrating, but since we made the shift in early 2023, membership has grown.
Thanks for all the passion you bring to your time on Medium!