The article says it does subqueries:

Getting the AST is a big step forward, but we still need a way to take your cursor position in the editor and map it to a path through this AST. Otherwise, we can’t know which part of the query you're interested in previewing. So we built some simple tools that pair DuckDB’s parser with its tokenizer to enrich the parse tree, which we then use to pinpoint the start and end of all nodes, clauses, and select statements. This cursor-to-AST mapping enables us to show you a preview of exactly the SELECT statement you're working on, no matter where it appears in a complex query.