Explanation
The following considerations should be included when configuring the report with branch management reportable objects:
Bankers with Branches with Opportunities, Accounts, Leads, and Contacts report types are available for creating reports with Branch Unit Related Records. These are standard report types that allow users to create reports that show data from Banker, Branch Unit, Opportunity, Account, Lead, Contact, and Branch Unit Related Record objects.
The reportable objects include Banker, Branch Unit, Branch Unit Related Records, and Branch Unit Customer. These are custom objects that are part of the branch management feature in Financial Services Cloud. Banker is an object that represents a banker or an employee who works at a branch unit.
Branch Unit is an object that represents a physical location where bankers provide services to customers.
Branch Unit Related Record is an object that represents a record that is related to a branch unit, such as an opportunity, an account, a lead, or a contact. Branch Unit Customer is an object that represents a customer who has a relationship with a branch unit.
When Branch Unit is the primary object, the administrator can select Branch Unit Customers or Branch Unit Related Records as related objects. This means that the administrator can create reports that show data from Branch Unit and its related objects by using lookup fields or junction objects

Explanation
Interaction Summary is the Financial Services Cloud feature that should be recommended in this scenario.
Interaction Summary is a standard object that represents a summary of an interaction with a client or a group of clients. It allows the user to capture meeting notes, specify confidentiality level, link related records, and associate interaction participants. Interaction Summary can be created from the Interaction Summary component on a record page or from the New Interaction Summary action on a list view or related list.
References: [Interaction Summary Object], [Create an Interaction Summary]