Adding earthworms to your bokashi soil factory is great idea. It is the worms (and other biota) in your soil which will break down the bokashi pre-compost. Just be careful as the bokashi pre-compost is acidic and can be harmfuk to worms therefore make sure to add your earthworms to the top of the final garden soil layer (not in contact with the bokashi pre-compost).
Hope that helps
Nicki and the Bokashi Living team