You should always use SAP_WAPI* functions for everything related to workflow. The "WAPI functions" are kind of an official API for the workflow. Many times the WAPIs eventually call the SWW* functions.
But as said before: "Use SAP_WAPI_WRITE_CONTAINER"! It shouldn't differ much from SWW_WI_CONTAINER_MODIFY.
Kind regards,
Karri
