When the market's feedback changes your teaching or your product, say so — in the community, in release notes, in the revised lessons themselves.
Members who see their threads produce change contribute more and better; the feedback loop, made visible, becomes a reason to participate in it. This is also the cheapest trust play in the book: nothing signals listening like a visible edit.
The loop closes
Publish what you fixed and Stage 04 feeds Stage 01: the revision is new Express material, the contributor is a warmer champion, and the next turn of the loop starts with more trust than the last.