I did not manage to get the braun stains off by using rim cleaner spray.
Any other things I can try?

 

most rims are painted with clear coat just like the body. Almost looks like that staining is bits of ceramic brake pad so its something that has stuck to the rim which may require some light compounding cleaner or clay type cleaner to remove. You can also apply auto body polish to help protect the clear coat as well.

 

I tried cleaner as well as scratch remover. Did not help.
Looks like it are rust stains...
Any way to get that cleared?

 

try this - take a product like Barkeepers Friend (a household cleaning product that's a very fine compounding grit) shake some out and dab a damp finger to pick some up. Now rub an inconspicuous spot with the stain to see if you can mechanically rub the rust off the finish. this is a bit more agressive than using a polishing compound like "No. 7" (ie scratch remover/paint cutter). I think you need to determine if its a stain that's sitting on top or if something that's bleeding through.