There are risks in this, because both parties sign the contract, which means that they have reached an agreement on the solution. If the final effect is not obvious, it is the responsibility of the consulting company and yourself, because you also agreed to this plan at the beginning.
At present, I suggest that you first confirm whether the scheme provided by the consulting company is effective, and if it is effective, sign the contract immediately, so that you can get legal benefits. You should not pay the full amount in the early stage, but should make up with the progress of the consultation. For example, paying 30% at the beginning and paying 30% when the progress reaches 50% is a guarantee for yourself. But it doesn't have to be like this, and the specific situation is analyzed.
Although the air ticket can also prove it, if you really go to court, the contract is the most legitimate interest. It is suggested to sign the contract quickly.