Does any portion of the agreed-upon dowry advance remain an obligation upon the husband after the marriage, according to prevailing custom?

If the forward mahr was agreed upon as 25 mithqals of gold, and 15 mithqals were purchased for her and delivered, and the local custom is that the contract includes stipulations that are not binding unless divorce or death occurs, and what is considered binding is what was actually agreed upon, purchased, and delivered, then the husband is not obligated to give the remaining ten mithqals. However, if this custom is not prevalent, and it was not referred to during the agreement, then what was agreed upon, namely giving 25 mithqals, must be fulfilled, and ten mithqals remain outstanding as a debt upon the husband. It is advised not to write anything in the contract that contradicts reality, in order to avoid disputes.