I am a broker with strict policies as to when my salesperson can sign a Compensation Agreement Between Brokers on behalf of the firm. One of my salespersons violated that policy and signed a contract they never should have signed. Is my firm bound by that unauthorized contract?

Yes, your firm will be bound by that contract (unless the other broker knew that your agent did not have authority to sign the contract). As a general rule, parties are permitted to assume that the person signing the contract on behalf of the company had the authority to do so. Your remedy, if any, is against the salesperson who signed the contract.