w201 Battery Tray and Passenger Wheel well rust

[Babybenz91]

Thought I would get some opinions on this, for a while I have been aware that the battery tray area of my 91 190e (not my daily) was super corroded. As for the wheel well, it is mostly rust free except a small hole and surface rust. Fortunately because the car was been mostly covered/protected it has not spread excessively. I am in the process of preparing to remove the rust out, and have someone weld in patches for me (reputable guy, runs a small local body shop fair price and has done work for some friends in the past.) Luckily I have experience with rust, and I have a complete 92 parts car that will provide patch panels for me. My question is about how the area under/around the battery is supposed to drain. I have not replaced the seal on the right side (air inlet cowl to hood), but I have determined that the drain in that area is clogged, so it is on my agenda to clear out. Aside from that I have noticed a hole (looks like a factory cavity it is not corroded), and recently lined the area with some baggies before a rainstorm. The result was a considerable amount of water ended up in the bags. I have tried looking at xentry, manuals, and pictures of other 190e’s but am unable to determine what is causing the poor draining of the battery area. I would like to have this figured out before getting the area repaired, any insight would be appreciated.