Trusting is a problem, to be honest, mostly for fun. If you want to trustable source, feel free to copy text paragraph and let it parse for you, there is another mode for that.
So it's a pretty simple wrapper of LLM model in use (currently gpt-4o), it does not add much technical stuff in it.
It does not use database for any "random search", but yes, columns.ai is a data analytics tool that allows you to connect supported live data sources like Google Spreadsheet, Airtable, Notion Database to create visual stories.
The analytics engine is home built (https://github.com/varchar-io/nebula) but it is not a database. And I don't use LLM agents, just build logic how to purify data returned by LLM, and fit them into an optimized visualization.
Unless it's very "public common", otherwise, the numbers can be used for trustworthy work. In general, I think this is just for "fun play" most of the time.