If waterproofing the fabric part of the roof solves it temporarily then it seems like you probably have tear in the canvas.
Mercedes clk convertible leaking roof.
Hydraulic leaks or hydraulic pump failure.
Common mercedes clk soft top roof problems.
My 2006 clk 500 roof leaks when it rains.
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.
Alignment issues with roof frame.
Roof requires recalibration or roof reset.
Convertible roof is stuck open shut.
Boot lid catch does not release or you are unable to access boot area.
The majority of mercedes convertible problems are caused by a bad relay weak lift cylinder or lift cylinder leaking by the o ring.
My 2006 clk 500 roof leaks when it rains.