One of the real attractions to Roon was that I could finally find all instances of a track in my collection, regardless of who performed it. This has, however, proven not to be the case because Roon doesn’t fill in the blanks on composer metadata even when it has the unambiguous data to do so. As a workaround I started doing so myself using the same composer names that Allmusic/Rovi/Tivo do. For a while that worked wonders.
Now, however, Roon has taken to adding noise to composer metadata, meaning that tracks that would previously have matched now no longer match. 
From Roon’s entry for Encomium: A Tribute to Led Zeppelin:
Per allmusic.com:
From Amy Lee - Recover, Vol. 1
All of the abovementioned albums are tagged with Jimmy Page and Robert Plant credited as Composer.
If I look up all instances of that track Roon shows 23, but there are more. Amy Lee doesn’t show up (and I suspect there are many more…in fact, on the assumption that Roon’s filter is accurate, there are 34!).
It seems one of the contributing reasons is because Roon arbitrarily added additional composer entries for some instances of the track but not all instances. C’mon guys, where is the normative data model for Composers? What are the common denominators here to some tracks being seen as the same by Roon and having lyrics matched vis a vis those left out:
I’m tired of playing around with Roon and metadata trying to guess what it does so I can get to it to what it was touted to do in the first place. Can you guys please put out some definitive info re what it takes to match tracks and so on so that those of us who care can actually get some value out of Roon beyond pressing play!