So what I can gather from this Github Issue and using the Wayback Machine, the doco use to involve using Actions on Google console. However, this has since been removed as this was deprecated by Google.
However, the 404 errors on request sync section still references Actions on Google console which now makes no sense. I was very confused until I figured out it had since been removed.
Does this whole section no longer apply, ie. does testing no longer expire around 30 days? Or is there some new of fixing this issue that uses Google Developer Console that hasn't been documented?
Also, this description of the configuration values are out of date
project_id string Required
Project ID from the Actions on Google console (looks like words-2ab12)
Thanks for your help 🙂