Not considering because we no longer support AI professional. This has been superseded by the OpenAI Provider for Trados. In the new plugin the system instructions for the prompts are dynamically generated considering the segment content & the settings selected by the user from the UI. It is designed in this way to optimize & reduce the amount of tokens communicated with each request to the AI technology. It is also for this reason that it is not editable by the user, especially as there is an expectation on the result being returned in a specific format.
However, going forward the intent is to expose this functionality & enable users to write their own persona system instructions to associate with the user prompts. This will be communicated in due course, once it is available with later builds of the current plugins supporting this technology.