This is partially because you cannot clone a non-transient object to a transient object or vice versa, so any mix usage of transient databases or schemas and non-transient databases or schemas does not work well here.
I am happy to open a simple PR if this is a desired feature.
Ideally this would have the simple option/argument for the macros to make the databases and schemas transient.
https://docs.snowflake.com/en/sql-reference/sql/create-schema#optional-parameters
This is partially because you cannot clone a non-transient object to a transient object or vice versa, so any mix usage of transient databases or schemas and non-transient databases or schemas does not work well here.
I am happy to open a simple PR if this is a desired feature.