It appears having nested object relationships that have backend only insert permissions breaks schema introspection when the parent object has insert permissions without the backend only flag set. (For the same role)

Error produced when:
Parent Table Insert: backend-only = false
Child Table Insert: backend-only = true

No error is produced when both the parent and child insert permissions have the same value for backend-only.

The server outputs this error:

"error":{"path":"$","error":"type info not found for: 'audiences_obj_rel_insert_input'","code":"unexpected"}

Server Version: 1.2.2
CLI Version 1.2.2
Metadata Version: 2