I guess the squeaks and rattles is all about the play of different components which have developed over the years
Let me start of by saying that I will not be able to give a perfect formula as to how to fix a certain issue; I will only be able to give you some pointers based on my own experiences.
We need to realize that the whole “barn-door-assembly” is not the best design.
We are dealing with numerous locking mechanism hinges, guides strikers etc. + weak design of the barn door and welding. All this is exposed to forces and it becomes week and loose as years go by.
The first thing was actually done by G-Tech when I had my first service done. He inserted ~ 1mm self-adhesive foam seal around the area where the normal rubber seal is fitted but on the door opening / car side not on the actual door. This improved the situation a little bit because it increased the tension between car and barn-door.
Furthermore I have done the following:
RH side barn door part which also carries the spare wheel: Checked if this part of the door has sagged over time. At the bottom of the door (inside) there is a round bolt like striker which moves into a u-shaped “catch” (mounted to the vehicle at opposite position) of the “round striker” . In my case this round striker was sitting slightly lower compared to the u-shaped catch. In order to improve this situation a loosened the door hinges and lifted the door with the assistance of a hydraulic lifter and re-tightened the hinges. That resolved the sagged door-issue.
The striker on top / middle of the doorframe can be adjusted by loosening the two screws and pushing the striker inwards by 1-2 mm. This will also increase the tension on that part of the door and reduce rattles. The striker is covered with a plastic coating. If this coating is damaged than consider replacing the striker. I have tried to improve this with some insulation tape. This works at first but was only a temporary fix as the tapes starts coming of over time.
I have also opened up the inside door panel and filled it with insulation material + I taped up some of the connecting rod to the doorlock mechanism to reduce play and potential rattles.
It might sound all like a “boer mak a plan” but these measures improved the rattling in my car by about 50%