I'd like to offer various suggestions or fixes (where I can).
Ideally, you can immediately send pull requests with the documentation improvements, no need to discuss it or open issues.
(...) inconsistent organization. (...) Is creating issues on Github the preferred mechanism for initiating such discussions?
This might be already discussed at some point, search these issues to see if what you had in mind has already been brought up.
If it wasn't, feel free to either open a new issue or discuss it here in this thread.
I run on the same problems you listed in your intervention. What I did was to create a group for writing a book on Nim. Here is our github page:
https://github.com/FemtoEmacs/nimacros
If you want to collaborate with proofreading or even writing a chapter, feel free to do so. By the way, the group is also trying to improve the nim-mode of the lem text editor: