Is it permissible, from a Sharia perspective, for the marriage officiant to add a written condition to the marriage contract that was not verbally mentioned in the offer and acceptance, knowing that all parties implicitly agree to the condition, and how can this procedure be rectified?

The condition agreed upon between the husband and wife does not need to be mentioned when the officiant (ma'dhun) pronounces the offer and acceptance. There is no harm in documenting it in writing, even if it is not verbally articulated. It does not require gathering people to verbally pronounce it, and the husband is obligated to fulfill the condition. It is advisable to refer to the Sharia court in case of a dispute.