A couple of thoughts:

1. Unfortunately, a lot of our instruments do their own sampling so the sampling rate and unit aren't embedded in in the streamconfigs API response. You're going to have to do detective work to track that information down and create a mechanism to keep it up to date. While you're doing that detective work, however, if you do spot instruments that can be migrated to using the sampling mechanism baked into EventLogging, then absolutely do the migration!

Later versions would allow exploring and previewing the schema data - a capability that's been lacking since we migrated away from wiki pages

This is provided by DataHub. Could the problem as stated by solved more immediately by keeping documentation and tags up to date there?

3. There is a decent overlap between this and a project that the Metrics Platform team is planning for FY2022-23 – a control panel for event streams. The control panel will allow you to list, create, update, and disable event streams via a UI. We're fleshing out the work in T330354: [Goal] Build the Metrics Platform control plane. Following on from my first comment, the control panel will need to provide a mechanism for the user to specify the config variable that defines the sampling rate with the stream.

None of this is to say "Don't do it that way!" There's a definite need here and I'd love to talk about it with Readers Web more.

Update: I make a bookmarklet [1] which addresses Jennifer's immediate needs for understanding how our click tracking works and possible values (our main problem is we use raw strings rather than enum which is great for extensibility, but documentation not so much. I have to duplicate the logic in WikimediaEvents for this to work but it's good enough. I could also expand this to include the existing sampling rate (where available) which might provide momentum for moving sample rate declarations into the instruments.

[1] javascript:mw.loader.load('https://en.wikipedia.beta.wmflabs.org/w/index.php?title=MediaWiki:EventLoggingHints.js&action=raw&ctype=text/javascript%27)

Discussed with the team and decided that we probably want to convert this task into a spike to look over potential solutions.

Jennifer and I met and we have devised a plan to build out Infobox type content within DataHub. Notes here Touch base with @Jdlrobson when he gets back to sign off