Once the color is changed I doubt if you can go back. I use 1200F engine paint for the calipers and the low pH stuff doesn't bother it. Non-clorinated brake cleaner will though.
I just repaint the calipers every time I rotate tires with the spray can. Can't keep the brake dust out of the...
"not the core (...how hard would that be to change myself, with little skill?). "
Not an easy job at all. Maybe a 2-3 dayer if you've never done it before.
If you can smell it while driving it's got to be the heater hoses. Just get some 5/8" and 3/4" bulk hose and a 5/8 x 3/4" adapter.
You can replace all the hoses on you SHO with bulk hose with the exception of E9DZ-8548-B Short "C" shaped hose at oil filter and E9DZ-8548-FA 2 1/2 long X 2...
Sounds like it is a caustic type cleaner (high pH). Probably won't hurt the wheels and was just the type of paint the calipers had that is affected. I personally like the Espree green organic acid base (low pH) type that AutoZone sells.