To ensure the data is loading into the correct fields in Financial Services Cloud, the consultant should utilize a field mapping file with the external system allocation and the corresponding field in Salesforce. A field mapping file is a file that specifies how fields from an external system map to fields in Salesforce. By using a field mapping file, the consultant can ensure that the data from the new custom object is imported into the correct fields in Financial Services Cloud and avoid any data loss or inconsistency.

Explanation
Salesforce offers various tools and capabilities to integrate Financial Services Cloud with external systems, such as core banking, insurance, or mortgage platforms. Some of the tools and capabilities that a consultant can recommend are:
Industry Integration Solutions with the MuleSoft Anypoint Platform: These are prebuilt integration solutions that leverage the MuleSoft Anypoint Platform to connect Financial Services Cloud with common industry systems, such as Fiserv, FIS, Jack Henry, and Guidewire1. These solutions enable bi-directional data synchronization, orchestration, and transformation between Salesforce and the external systems2.
OmniStudio Integration Procedures: These are reusable components that define the logic and sequence of steps for integrating data from external sources into Financial Services Cloud3. Integration procedures can be triggered by events, such as a button click or a record update, and can invoke other components, such as DataRaptors or OmniScripts4.
OmniStudio DataRaptors: These are data transformation components that can extract, load, and manipulate data from various sources, such as Salesforce objects, REST or SOAP web services, or CSV files5. DataRaptors can be used to map data between different formats, perform calculations or validations, or create or update records in Financial Services Cloud6.
References:
Industry Integration Solutions
MuleSoft Anypoint Platform
OmniStudio Integration Procedures
Create an Integration Procedure
OmniStudio DataRaptors
Create a DataRaptor

To grant restricted accessto users like Bank Tellers who need only limited access to Financial Services Cloud features, the Admin can use Financial Service Cloud Basic permission set license. This license enables user access to a license with contractual restrictions for FinancialServices Cloud and provides access to core objects such as accounts, contacts, leads, opportunities, cases, activities, reports, dashboards, and custom objects. This license also provides access to some Financial Services Cloud features such as Action Plans, Actionable Relationship Center (ARC), Branch Management, Complaint Management, Data Consumption Framework (DCF), Discovery Framework (DF), Document Generation (DG), Groups (Householding), Intelligent Document Automation (IDA), Intelligent Need-Based Referrals and Scoring (INRS), Referral Management (RM), Relationship Builder (RB), Relationship Groups (RG), Relationship Map (RM), Timeline (TL).