I don't think there has ever been a club sanctioned for unofficial payments.
For example, Barca were never investigated for paying for prostitutes for Neymar's dad, alongside all the other alleged extras in that transfer.
Tapping up players is also against the rules but never seems to be enforced.
If our accounts are watertight which the CAS case would imply then we should be fine. I think a fine and possibly small transfer ban for not cooperating/small breaks in the rules.
Someone posted earlier that Spurs got done in 1994 because they didn't disclose payments to players when a tribunal was basing the amount Spurs needed to pay for the players on their salaries.