This issue, while not explicitly defined in the message, appears to be a technical challenge that the sender is admitting unfamiliarity with. The sender is seeking clarification on the nature of the data availability problem related to LN-symmetry, indicating a gap in understanding or memory regarding the subject matter.

Unfortunately, without further details provided in the email excerpts, it's not possible for me to give a detailed summary or explanation about how CAT could resolve issues with LN-symmetry. Given the context presented, the email suggests a dialogue where one programmer is reaching out to another for insights on a specific technical problem which might not be commonly known or may require specialized knowledge in a particular field of programming or data science.