I don’t know of any way without sending a request.
From my understanding (which might be flawed), the main bot service sends an HTTP request with all the details of the conversation to the actions server. The actions server then processes this, and sends a response of what events the main bot service needs to do. If that’s the case, then it doesn’t seem like there’s a way to use the NLU from inside the actions server, besides making an HTTP call back to the main bot service, since the actions server doesn’t contain the NLU.
I think this is the API that was being referred to: HTTP API