Tropy creates two full-text indices: one for all metadata values and one for all notes. Currently, a query in the quick search box is matched against both indices and the result contains all items with a match.
The full-text index is built using a unicode tokenizer which removes diacritics and uses the porter stemming algorithm which probably explains the aetates/aetatis match.
For the first example, the match could also be in the metadata. If you select the item in question in the project view and hit Ctrl/Cmd+C
you copy a JSON representation of the item (and its notes) to the clipboard. You can then paste the full item here, then we can hopefully figure out why the term ‘age’ matched.
In general, the quick search functionality is powered by SQLite’s FTS extension; the query is handed to the extension almost as is and you can use some of the advanced features of the query language. In an upcoming release, we’re planning to provide more advanced search functionality via the UI. Currently you can only query the full-text index directly.