Maybe this will help you.
Sunroof Drain Hose Replacement
Important: When installing the new rear drain hose tie wraps, position the tie wraps in order to maintain clearance between the tie wraps and the headliner.
Notice: Use care when removing and installing the headliner. If reusing the headliner lay the headliner down flat on a clean surface. Excessive bending will damage the headliner.
You can clean them if they are not pinched or collapsed.The replacement parts will need to come from your Cadillac dealer.
The front drain tubes run down the A pillar & exit down into the fender.They are hidden & I am sorry that I do not have a better picture.