Tool to create queries like the one for filters?

The unity panel makes it easy to create filters, but I can't find an equivalent for searches.
I've been able to make simple word searches but don't know how to add boolean expressions or specify fields etc.
Is it possible to convert a filter into a query?

No, and Microsoft still haven't really documented the Windows Search query syntax in full, so it'd be hard to build a comprehensive tool to generate it.

Is it possible for a search to differentiate between upper and lower case?

A quick google suggests there is no known way to tell Windows Search to he case sensitive.

You can do it using Opus filters instead, though.

So, searches are limited but filters are great.
Why can't Opus filters be enabled for results to be saveable and auto updatable . . . like the searches?