I added estimates of the metal layer current density maximum values here: https://docs.google.com/spreadsheets/d/1oL6ldkQdLu-4FEQE0lX6BcgbqzYfNnd1XA8vERe0vpE/ at the bottom of the page "Layer Resistances and Capacitances". These values are based on the aluminum layer thicknesses. I don't know the equivalent values for titanium nitride, so I don't have a value for local interconnect, and I don't know the exact composition of their contacts, so I don't have values for the vias. From a thread in #analog-design