Thank you for stopping in :)
I believe their is an unbreakable connection between the Kabbalah and sacred geometry. The Tree of Life is the central symbol used in the Kabbalah and it is found within the Flower of Life. The Flower of Life contains all existing shapes and patterns on this plain of existence so it makes sense that they would be connected. They both tell the story of how we came to be and how we are able to continue to expand infinitely!
I don't understand energetic grids on our earth using the term "leylines". However, there are absolutely nodes on earth with exact mathematical points for a reason. The sacred sites serve as beacons of light, but even if there wasn't something built upon it, I believe that the energy would be just as strong there. I believe that the structures are the result of 5D energy manifesting in the material realm.
Your question has actually inspired me to look for some reading that discusses this topic further. I just found The Secret Doctrine of the Kabbalah: Recovering the Key to Hebraic Sacred Science . It looks like it really digs deep into how the Divine manifests in the material realm with specific sacred patterns.

What do you think about there being a connection between sacred geometry, the Kabbalah, and leylines?

Thank you for your thought provoking questions :)