My declarations of "being done" were rather premature. It took me a while to realize that once I pointed the "production" version of Toolhunt to the actual Toolhub servers, that I would also need to switch all of the Oauth-related URLs. I duly registered the tool with Toolhub and made the necessary changes, and it all goes smoothly at first, but on the final redirect back to toolhunt.toolforge.org, I end up receiving a 502 error.
I get the same results in Firefox, Chrome and Edge.
@bd808, any thoughts?