The majority of mercedes convertible problems are caused by a bad relay weak lift cylinder or lift cylinder leaking by the o ring.
Mercedes clk convertible leaking roof.
If waterproofing the fabric part of the roof solves it temporarily then it seems like you probably have tear in the canvas.
Hydraulic leaks or hydraulic pump failure.
My 2006 clk 500 roof leaks when it rains.
The most common source of leaks is in the rubber seals but it is also possible that you have a torn roof canvas.
Alignment issues with roof frame.
Roof requires recalibration or roof reset.
Cabriolet not operating fully through cycle or stops halfway.
Boot lid catch does not release or you are unable to access boot area.
If you find out that the convertible top reservoir is low in fluid that means that you have a leak most likely at one of the convertible lift cylinders.
It drips down on both passenger and driver side near where the window meets the closed top so drops fall on the seats near the windows not in the middle of.