Usage

Confluence settings → Mermaid Diagram settings → Usage lists every page and blog post that contains a diagram, with its space and when it was last changed. Search narrows the list by page title or by the text in the diagrams.

The list runs as the signed-in admin, so it shows only pages they can view.

Confluence search

Each diagram's title and the words in it are indexed, so Confluence's own search finds a page by what its diagrams say. The index is updated every time a diagram is saved.