The paint on Brembo calipers is powder coat,u cannot sucessfully touch this up.
Even if u cud anodise the calipers ,which u can't because they are castings, a winters use wud destroy it.
Peeling powder coat is probably caused by a combination of faulty original application ie the calipers were not fully degreased before coating , the operating environment , hot/cold , hot/cold , winter salt , wheel cleaning solutions , pressure washing , stone chips , heavy handed wheel fitters etc etc.
The only solution outside a warranty claim is complete strip and re-powder coat.
1/ this will be costly due to the work involved on those big , complex calipers.
2/ Where do u find new Brembo decals ?
This is where my philosophy on using my car has it's advantages , as in I may be mad but by not using my car in the wet or winter, everything is still virtually as new as the day I took delivery , both underside and topside