Unfortunately the voice recognition accuracy of these free form utterances many times is not good to the effect that when Alexa repeats my request, sometimes it is incomprehensible! In the latter case, I have found out that the accuracy does not improve if you just try to repeat your request. But instead of just stopping using Alexa for recognising complicated utterances there is an alternative hacky and somewhat inconvenient solution.
Specifically, you can review all your voice interactions with Alexa by visiting History in Settings in the Alexa App or in the Alexa web page.
There you can see a list of the transcriptions of all your interactions arranged chronologically and by clicking on the left side you can see the details for each one.
Now the important thing is that you can listen to the audio clip which was wrongly transcribed by clicking on the transcription.
As a result, you can hear back the request and remember what you wanted to do. Nothing is lost!
Additionally, you can provide feedback on inaccurate translations which hopefully will improve the voice recognition accuracy in the future.