Searching for Compositions of a particular Form for a Composer is very unintuitive. Ordinarily you would go to Mozart, say, and look for Concertos. You can’t separate them out so you give up.
In fact, what you need to do is go to Compositions, and use the Focus tools to specify Composer (Mozart) and Form (Concerto). This then results in a usable list that can be ordered in various ways and Bookmarked if desired.
But most people will just go to Mozart and get lost.
A year or so ago I made a compilation of the Feature Requests I would like to see in Classical. One of them (originally proposed by @evand) has been implemented now, being ROONALBUMTAG and ROONTRACKTAG. Fingers crossed for more.