Canvas Catalog's API is lacking parity with UI functions. For example, you cannot manage sub catalog admins via the API as you can in Canvas. This can pose a problem for institutions who have a large population of admins but want to develop a home grown solution for managing catalog admins on a more automated basis, or any other integration or use case that would improve the use of Catalog.
Develop an API for areas of Canvas Catalog where there is none. - Sub-Catalog Admin endpoints - Creation/Management of Sub-Catalogs - Creation/Management of Promotions - Audit Log I'm sure there are ones I've overlooked as well. Adding more API functionality will greatly improve how admins can interact with Catalog, eliminating processes that are too manual.
