Butane extraction, Alcohol or Acetone wash is more then safe as far as the mildew. The Brother's Grunt used to have a post in the hash section on how to make Alcohol quick wash hash oil No different for Acetone.
Butane extraction is trickier and requires tons of ventilation. My preferred method above even bud itself. But you want a ton of trim and hours to spend with oven mits on.
The HUGE key to all these methods is purity of the chemical used.
Acetone has to be 100% pure no solids which is expensive.
Alcohol Pharm Grade 98%
Butane at least triple refined. void of ANY methyl marcaptan (AKA Methanethiol,mercaptomethane,thiomethyl alcohol). Coleman's butane/propane camping gas being a huge no-no. I use Colibri.
As soon as any of the above mentioned chemicals touch the mildew it dies immediately. It just extracts all essential oils.