It will lock though, just not unlock, correct
The door lock actuator needs to be replaced and it is serviced as part of the door latch on the door itself. You have to take the door panel off and then go inside the door and
disconnect linkage and connector, then take 3 external bolts out, the door panel is the hardest part and they will break easily even if taken off properly at times, so if you don't have a lot of experience taking door panels off you might consider having someone familiar with cadillac door panels take it off, cause they are expensive to replace.
No there is not enough room, the door cannot be unlocked manually with lock knob then
opened up. And I told you wrong earlier the actuator can be serviced separately from the latch but you have to remove the latch and then take the actuator off of it.
I've seen 2 just like this, both times it was the door lock actuator that was bound up on the latch, the easiest way i found to get to the rods that attach to the latch was to bust out the outside door handle and it was still pretty difficult to get to inside of the door and
get it open.