Please critique my CRM design

Please critique my CRM design

I run a disability healthcare business with 2 business units. We run on Zoho One and are re-designing our CRM. We have developed the design concept ourselves, and I am hoping to get some critical feedback:
1) Noting that this is an early design of the module architecture and there are many items to be resolved, what gaps can you foresee?
2) What are the risks of our architecture? For example, we do not use a dedicated Leads module, as most instances do; what risks does this raise
3) What advice do you have for improving our design?
4) What advice do you have as we start to develop? We are using a developer that is a Zoho partner

See attached document. This document is not intended to be a finished specification; i is an early architecture document only. Certain areas remain intentionally unresolved, including:

Contact lifecycle
Service lifecycle
Renewal workflows
Blueprint design
Workflow automations
Detailed field definitions
Reporting requirements
OT assessment tracking