Currently, there is no way to edit the "created by user" field in Aha! Even though if you go to integration mappings, it allows you to map that field with the Jira "Reporter" field and allows you to toggle the integration to "2-way", yet Aha! Support has confirmed this does not work, and the created by user field can not actually be updated via the UI or integration. Please allow both of these options.
This field can now be updated through integrations and the API. We do not have plans to allow updates via the UI at this time based on historical customer feedback. But we will monitor that idea if it becomes a more frequent need.