Thanks for your replies, folks.
From going thru the forums I had found this thread, which implied that starting Roon Radio from a non-holiday track would exclude holiday tracks.
And in a separate discussion it was stated: “We’re investigating this one – we have long had a rule that prevented holiday music outside of December but we think a bug may have been introduced over the last few months”
That discussion was in this thread: Holiday music STILL gets played [Investigating]
It seems there’s been no further discussion since 2021, so my expectation that Roon should do this was based on discussion that it seemingly already did.
A big advantage for me with Roon is its having a more sophisticated approach to genres than Apple’s iTunes/Music app provided, but I’m trying to understand how much massaging of the data/files will be required…