What should be agreed at the proposal so that misunderstandings do not arise later?

Agree clearly on the key matters: the length of the engagement, the rough date of the nikah, the mahr, the gifts (hantaran) and what happens if the engagement is broken off. Many disputes come from things that were ‘assumed understood’ but never actually said. Also discuss who bears the costs of the celebration and where the marriage contract (akad nikah) will take place. Appoint one representative from each side to note down a summary of what was agreed and share it after the ceremony. That note is not a sign of distrust; it prevents different memories a few months later. If a dispute arises over compensation for a broken engagement, the Syariah Court is the proper place to assess it. See the custom of returning double.