Is the crystalline grid Kryon refers to, a physical structure within the earth that is attuned to the akashic records?

This is a metaphor, carefully chosen to provide a special imagery connoting the presence of important intention, and its continued presence as a kind of reservoir of knowledge and information important for human understanding, development, and future destiny. In effect, much of what you learn is a recycling of what has taken place heretofore, registered within the akashic records and thus, it is available to be repurposed and given to others, you included. Truly original things will similarly become available through the collective unconscious of humanity, as well as being in the akashic records. So this is a central mechanism for the conduct of life on all levels by all beings.