Yoshioka-san, there is no plan that I am aware of to create such an export to .csv.
The Developer Center does have information regarding the Public API calls to get the Roles associated with a specific User:
https://developer.mypurecloud.com/api/rest/v2/users/index.html#getUsersUserIdRoles
Or, you can use one of the API SDKs to get a list of users, then iterate through that list to get the Roles for each user, and write the results to a .csv file. The Python methods are listed at https://developer.mypurecloud.com/api/rest/client-libraries/python/latest/UsersApi.html and the other SDKs are documented in the same section of the Developer Center.