Will my Leyland cypress recover after water issues and shoring?

It is difficult to say without seeing the site and conditions. While it is possible for new roots to establish, the larger problem of the poor drainage in the area needs to be addressed for the long-term health of the trees. Excess moisture can create an environment that malignant fungal and bacterial organisms thrive in and be detrimental to the trees. Make an appointment and allow a certified arborist to evaluate the trees and the site to give you the best advice for your specific situation.