I agree with you it is confusing. It seems to mean that the bank could receive a check within the time period but that it might still be too short a delay to allow it to honour the check so that the payment is made on time.

It sounds like they are trying to cover themselves from all angles.

Very bad drafting. Contradiction in terms.

But you have no choice right?

Still, I would put a note for the client to protect myself as this has legal implications. I would mention that there seems to be a contradiction in terms and I would point how why it is so. Then propose the best possible translation. Maybe the lawyer who wrote this will come to his senses and rewrite it. It has happened to me before. Some clients like it, others are more susceptible. It is a matter of diplomacy I guess. Good luck.