Check out the Issue Explorer
Looking to fund some work? You can submit a new Funded Issue here.
Once we have the implementation working, we should start porting test cases from go-ethereum over (https://github.com/ethereum/go-ethereum/blob/master/consensus/clique/snapshot_test.go)
Also, we are bound to find consensus issues when we go live. Fixes should be accompanied by unit tests that capture the edge cases we find.