I check the v4.1 manpage: "Ranges or lists of names are not allowed."
And the crontab entry parsing source sports a familiar phrase:
/ no numbers, look for a string if we have any /
So vixie-cron v4.1 seems to support named weekday & month ranges & lists, same as cronie.
But then I vaguely seemed to remember seeing Paul Vixie's name on #techtwitter somewhere... and sure enough: @paulvixie
So... let's DM him. (Why not? Maybe he's as bored as I am.)