Answer
Altering the application-owner schema name away from the default is officially in a deprecation period — IFS recommends aligning to the default IFSAPP wherever possible, since most RnD installation/upgrade testing assumes it, and it's required outright if you ever move to the fully managed IFS Cloud service. Beyond the schema rename itself, be aware the application-owner identity is also referenced as plain data in many other tables throughout the schema (user, role, finance, procurement, and reporting tables among others store it as a foreign-key-style username string) — a full rename needs those data references updated too, not just the schema object itself, or various user/role/authorization lookups tied to the old name will silently break.