Should I work with a referral contact to write their referral submission for them?

Yes. If someone is referring you, draft the answers for them. Referral submissions are often a low priority for the person referring you — they have their own work to manage. Make it as easy as possible by providing the exact language they need to submit. For company-specific questions (like "Why would this candidate be a good fit for [Company]?"), anchor your answer in that company's values and mission. Your CSM can help you draft this; send it to them via email for coach review before your contact submits it.