This is just an idea, I have not tried this.
The queries needed IMO break down into uses based on duty
- moderator
- admin
- developer
As such the tables needed can be grouped into ever growing sets with the smallest set being the tables needed by a moderator.
Now, much of the data needed by a moderator will be based on common joins of tables with specific columns being needed, thus a view.
If the common views are used instead of the entire schema, then hopefully many of the prompts would only need to pass along the views and not the entire schema and thus make it much easier for the LLM to generate a possible solution.
HTH
For the much harder queries, odds are if you know enough to need such a query you know enough to build the query.