I would call this obstruction of justice.
Are you aware of a specific problem, or is there a plea deal to spill something meaningful? Comey has either perjured himself or given false statement before Congress, has he not?
I've successfully bargained down moving traffic violations with the prosecutor prior to trial on a couple of occasions. Have even had charges dismissed before. Comey is high octane by comparison but bargaining model is still applicable, I think.
FReegards!