You can make the z much more stable if ou take off the rigid pieces to the vac hose and connect the hose directly to the mount. The rigid pieces act as a lever arm and most definitely move the spindle around as it moves, even though you did a great jot of keeping the hose slack it will affect accuracy. You can test this quickly with a pen and draw two very large squares or circles, one with the lever arm one without. You should see a difference.
Also I can tell if it is or not but the router cord should be zip tied to the gantry to avoid the same issue, along with the hose if possible.