Regarding the bad flips:
Maybe the team can implement a pre-validation flip verification, so the bad flips don't land on the Short session. The long validation can remain the same.
For example some humans apply to become super-verifiers which will verify part of the submitted flips and tag them "good" or "bad" from the already submitted flips (let's say 48h before validation starts) and make a pool from wich the flips will be chosen for the Short session.
Of course the super-verifiers will be rewarded extra for their effort, like master-nodes, if you wish.