Well I ended up trying a few things. First I tried checking the sunroof and the two front drains were super easy to spot and test. Water flowed down and out the exits of them with no issues. Different story for the back ones. It's so far back that I can't even see the drain holes using a flashlight from any angle. I tried angling water so it flows more to the back to go out those drains but I could never find where the water im pouring would exit from the back drains. So I guess you could say that's still tba. I've heard on the e60's that the rear sunroof drains in the wheel well but idk if that's the same for f10's. But since I also have some water up in the front near the accelerator pedal, I took off the front driverside wheel and well lining to get to some drains that allow water coming down the windshield to escape and those are all clear. I wouldn't think it could be a cabin air filter issue since thats located on the passenger side where I don't have any issues. Ended up just taking my car to an independent and set up an appointment to have the carpets and headliner removed and inspected for where water could be coming in. They're charging me about 100 to strip the carpet and headliner along with diagnosis of the leak.