Hello!
It would be useful to expand the search field and add some utilities to it. For example, provide it with intellisense technology, auto-fill, as-you-type suggestions, visual help that colors errors, and the elements of the search. In short, that facilitates to build complex searches, structured and visually friendly. Just as the code editors do.
I've been a proponent of the cookbook (which most users never recognized as a template), the templates (which are so woefully underpopulated as to be little help), simplification attempts (Bible browser, morph document), railroad diagrams (which appear to be popular only with myself) .... I love the idea of it behaving like a code editor which is easily tested as most code editors allow you to define your own grammar. However, have you tried to convert the search syntax into a grammar? It is an interesting exercise as the resources being search feed back into the legal grammar.
Orthodox Bishop Hilarion Alfeyev: "To be a theologian means to have experience of a personal encounter with God through prayer and worship."