you need to re-seal the water barrier.it is a black foam like cover that attaches to the door to avoid water spillage over to the door card and into the cabin.
if your seal is bad,heavy rain will pour in and over thru to the courtesy light and into the rear pax footwell.happened to me.i initially thought my sunroof drains were blocked but it turned out the water barries seal was not sticking properly.resealed everytinhg up and has been dry since....even after car wash or heavy rain