In my years as a competitive archer, imagery exercises had help me prepare and train for competition. During training, it helped me to visualise and work towards a shooting form. My mental skills coach had helped me using imagery to manage my feelings or do corrections to my techniques. I remember he mentioned that the mind cannot tell what is real and unreal in our imagination and by using imagery, it had help us overcome some of our conscious restriction in performance in our mindset.
In your exercise, the first part evolves different feeling and feeling, like rainbow gave a sense of joy, aroma of coffee evolves Alertness and at the same time, anchored me to calmness. The second part like the coffee exercises evolves a mixture of feelings and emotions.
Conclusion, Imagery is a powerful tool to use but personally, you got to have a good mental skills training coach to maximise this tool to maximise performance.