Log more stuff
When possible, anything that alters the database should get an entry in the activity log. This log will be used for investigating fraud, and can be used to replay the entire liferun of the system. It is also used for generating timelines and user visible transaction logs.
Put as much information as possible into each entry. Disk is cheap!
At least being able to look into patterns in trades is critical since this is one of the bullet points in the contract.