I'll admit that I haven't used Sonax Fallout Remover but I am extremely skeptical that it can remove rust. I do definitely believe that it will dislodge loose iron particles and that "orange dust", but oxidation needs to be chemically stopped or mechanically removed from the metal. That said, if it's just a little bit of "turning orange", you could clean it with that fallout remover, paint over it with a dab of touch-up, put a dab of clear over top, then wetsand it flat. Should last a pretty decent while before the rust causes the paint to bubble. By the time that happens, it will have eaten into the metal more, so sanding it off will likely reveal deeper etching that will need filling and a broader affected area.
Rondex touch-up paint is pretty good with the colour matching most times, but it's quite expensive at over $20/can and the coverage is terrible. The Rondex rattle can clear is hands is super finicky. If it's too hot, it won't set right. If it's too humid, it won't set right. The nozzle sucks absolute ass and is pretty likely to either dry spray into your wet coat, or lob a loogie of clear onto the surface that you'll then have to sand out. I've gotten a very nice mirror finish with it, but it absolutely needed wetsanding and buffing to do it. Once that's done though, it's decently tough and looks good.
Depending on the expanse of the affected area, you could attempt a blend with rattle cans, but believe me, it's easy to screw up. I know I screwed mine up, and it was simpler than a hood. I have a lot of wetsanding and buffing to do. I had some flaking paint on the lip of my wheel arch, so I sanded it down to bare metal and feathered out the area as little as possible, then scuffed a large area around it with a gray pad and sanding paste. (this is actually my mistake- I should have scuffed the entire fender or at least a larger area and recleared the whole thing) Then I primed, then blended out the repair with Rondex colour matched base, and cleared over the entire scuffed area. Getting Rondex clearcoat overspray on unscuffed areas was my downfall. I'm now stuck having to feather it out while trying not to burn through the factory clearcoat. Definitely don't do what I did.