OK, so here’s the first update.
The new Bosch wipers seem to be performing well. I also cleaned the windshield with the vinegar mix mentioned earlier. I used then in light rain condition, which was the worse for me, and everything went well.
Looking in my garage, I found all the wipers I tried so far. I have 3 Motorcraft wipers so I assume one broke at some point some years back. These wipers indeed have a reversed wind deflector on each side. Obviously, if I have two sets (with one wiper missing), I had them replaced at some point. I remember mentioning the rattling problem to the local repair guy last spring 2022.
Then I went to Canadian Tire and bought some “Certified” brand wipers. Seems that these wipers are very cheap (like 12 bucks CDN each). They seemed to work for a few months the the problem returned. These wipers are interchangeable, meaning no left or right side. When I removed them yesterday and compared them to the new Bosch ones, the former were very soft, easy to bend and twist.
Obviously the Motorcraft ones were not working well. As for the Bosch, they are also interchangeable, meaning not left or right specific.
Finally, I still had one box of the original Motorcraft ones and strangely, that box originally contained a 27 inches wiper with part number ending by B. Wonder why I ended up with a 27 inches one after obviously purchasing these wipers through a Ford dealer. Is it possible that Ford recommends a 27 inches one one side and a 28 inches on the other side? I didn’t phone them to ask.
S’il far so good with Bosch but winter is only beginning. No streaks, no rattling so far.