Has anyone been logging all the unrecognized user requests? Maybe to a google sheet?
In this way, you could go back and train your bot to better answer user questions over time?
Similarly, has anyone built a slick method to show the first unrecognized response, and if the user subsequently again enters something unrecognized, you use a second, different response. One that recognizes that the user might be getting frustrated, or perhaps is quite confused. One the third such subsequent unrecognized entry, you might then ask if they would like a human to help.
I would think that these two things would be something somebody has solved!