Expose `_audit.lang` and `_audit.brand`

We should add some public methods to get this metadata information instead of having to go through `_audit` to get them.

Start by locating the code that defines or exposes `_audit.lang` and `_audit.brand`, then inspect nearby tests and public API patterns. The work is done when callers can retrieve both metadata values through public methods without accessing `_audit` directly, with tests covering the new methods.

Written by the indexing model from the issue text.