If anyone finds that their plugin wasn't working, I recently realized that you the damage scale section has to start with a "1" parameter. I assumed (incorrectly) that the "interim" damage would linger until the next time and placed my first parameter at 23 hours..
As an example this is what I am using that is now working. Damage increases from 0% during 24 hours up to 100% after four days.
"damageScale": {
"1": 0.0,
"23": 0.1,
"47": 0.25,
"71": 0.5,
"95": 1.0
},