If I read that right, you caused your decals to peel by polishing first. Don't polish before installing your decals.
Personally, I don't typically use acetone to clean. I use Purple Power and bleach in a spray bottle, then use a cloth to get all the grime, then hit with a power washer. Dry with compressed air and a towel, and let air dry for awhile, then install the decals. They never come off, and I use Ebay decals as often as the OEM ones.
If you spray your cowls with fresh paint, wait a day, then install the decals. As the paint cures fully, it locks the decals on and they will be very, very difficult to remove. They certainly won't peel off, unless the paint isn't bonded well. Just be VERY careful to install in the right spot the first time, otherwise you will never get it to move without damaging your paint.