We had almost the same thing happen in our old place in Edmonton, found the soggy spot near a window about 6 months after a freeze thaw cycle. The leak path ended up being way higher than where the water showed, it had run down the inside of the exterior wall for like 8 feet before hitting that spot. What actually helped us find it was a cheap moisture meter from Home Depot, we poked around the drywall in a grid pattern and the readings got higher as we moved up and toward the corner. Ended up cutting a small hole up near the eaves to confirm and yeah, same story with the squished baffles, we fixed em by pulling back the blown in insulation and shoving in those hard plastic vent chutes that actually stay put.

Used to soak everything in ultrasonic cleaner" yeah I went through that phase too. Now I only bust it out for chains and small fiddly bits like derailleurs. For frames and cranks I just use a brush and degreaser, way faster and honestly gets the job done. The ultrasonic does a great job but it's a pain to set up and clean out every time. Plus I ruined a set of bearings once by leaving them in too long, that taught me real quick to respect the damn timer.