I also found that the rubber gasket around the wiper motor housing showed signs of not completely sealing and whilst there was no evidence that water had passed through I went to town on it too. See image
Finally, I found that water ran off the windscreen, over the scuttle/A pillar/inner wing junction which I had repaired, along the channel between the inner and outer wing, down the engine side of the inner wing and once again onto that main wiring harness and through into the passenger compartment. It was even getting through the self tapper holes which hold the wing on. I plugged the channel at both ends and made small rubber washers for the self tappers.
Eventually I also made a rough shroud type affair sikaflexed to the bulkhead to deflect water if it got past the other repairs.
All of the research and repair that I did went on over about two months during that almost continuous heavy rain that we had earlier in the year. It was extremely frustrating to have repeatedly found after a repair that the footwells were wet but the realisation that there are potentially multiple failure points meant perseverance was the only solution.
Incidentally, it is worth removing the glass-to-inner rubber seals on the sun rooves, cleaning the seals and the channels that they sit in to make sure that they are in order and that the glass ‘crushes’ the seal when closed appropriately so that h20 can’t even reach the troughs/drain tubes.
I also gorilla taped the sunroof - gasket to roof and glass to rubber seal and the alpine window seals so as to eliminate/isolate them whilst I was working on all of the aforementioned front windscreen issues. Otherwise you jus end up chasing your tail!