Quote: "So does freezer damage soft magnet? Isn't it some kind of rubber?"
I'm pretty sure a freezer would help the magnets keep their undesirable shape. The material might even contract and bend even more. I really don't think you'd damage a magnet with slightly raised temperatures, but what do I know
maybe make up some sort of contraption to heat the magnets without water. Water underneath a pan perhaps?
Looks like this is the temperature you don't want to be above "Curie point—about 570° C (1,060° F)." You'll probably be okay
Another source said 310° C. I'm sure it varies with materials, but they all look like quite high values to me.