You are going into great detail about how our brains might perform data retrieval, but this says nothing about what initiates the initial request for the data or how the request is made. Your thought experiment reveals nothing about what drives our thought processes. Have you considered the thought processes involved in solving a cryptic clue in a crossword? Do you still maintain that it all comes from the subconscious before we become aware of it?
Your subconscious knows all about your desires and intentions and preferences and acts on them on 'our' behalf. In the thought experiment, Berlin was yielded up to 'me'; somehow it decided of its own accord to come up with Berlin, not London, not Paris, not Madrid. It is making choices on my behalf without 'my' guidance.
We are familiar with this in fast moving situations where conscious thought would slow us down. A cricketer getting ready to swing his bat is making complex calculations derived from ball speed and trajectory and his subconscious mind is instigating hundreds of individual muscle movements in response completely without conscious intervention in order to play the ball.
So, as to your question '
what instigates an initial request for data' we have to bear in mind, that nothing occurs in isolation, thoughts trigger other thoughts; the desire to do the thought experiment for instance in the first place might have been triggered by prior suggestion (perhaps from me). All thoughts are processed through subconscious mind first. If you hear someone asking something of you for instance, those patterns of compression waves need to be processed through various levels of perception and cognition before conscious mind 'hears' it and understands it, by which time, your subconscious mind, running ahead, has already started responding, already started to deal with the request